PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Physical function”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,387 records · Page 77Linked to original sources
PubMed2003

Health-related quality of life in Australian adults with renal insufficiency: a population-based study.

BACKGROUND: Health-related quality of life is increasingly recognized as an important outcome in clinical research and patient care. Although there are a large number of reports of quality of life in the setting of end-stage renal disease, the impact of lesser degrees of renal impairment in the general population has not been described. METHODS: Data relating to quality of life measured by the Medical Outcomes Study 36-Item Short Form (SF-36) was available for 10,525 participants (93.6%) of the Australian Diabetes, Obesity and Lifestyle Study, a randomly selected representative sample of the Australian population aged 25 years or older. Results are examined by category of renal function (Cockcroft-Gault estimated glomerular filtration rate: normal, > or =60 mL/min/1.73 m2; renal insufficiency, <60 mL/min/1.73 m2). RESULTS: Significant impairment in health-related quality of life was seen with renal insufficiency for all SF-36 scales except Vitality and Mental Health. Adjusting for the substantial comorbidity associated with renal insufficiency, scores for Physical Functioning, Role-Physical, General Health, Vitality, and Role-Emotional were significantly lower. Examination of age-specific effects on health-related quality of life showed that mental health was particularly impaired in the younger age group, and Physical Functioning, in the older age group with renal insufficiency. Patterns of impairment were similar in men and women. CONCLUSION: Results from this study indicate that the current emphasis on clinical interventions aimed at preserving renal function are likely to improve the negative impact of kidney disease on health-related quality of life; however, prospective studies are needed to confirm these findings.

Adult↗
PubMed2006

One-year prospective quality-of-life outcomes in patients treated with angioplasty for symptomatic peripheral arterial disease.

BACKGROUND: Despite lower reported patency rates than open bypass, percutaneous transluminal angioplasty (PTA) may result in symptom relief, limb salvage, maintenance of ambulation and independent living, and overall improved quality of life. The goal of this study was to prospectively assess quality of life and functional outcomes after angioplasty and stenting in patients with chronic leg ischemia. METHODS: From August to December 2002, 84 patients with 118 chronically ischemic limbs underwent PTA with or without stenting as part of an ongoing prospective project performed to examine management of symptomatic peripheral arterial disease. All patients completed a preprocedure health questionnaire (Short Form 36) to provide adequate baseline data. Each patient was followed up every 3 months after treatment for 1 year to determine traditional outcomes of arterial patency, limb salvage, survival and amputation-free survival, and functional outcomes assessed according to improvement in quality of life, maintenance of ambulatory status, and maintenance of independent living status. The entire cohort was analyzed, as were subgroups of patients with lifestyle-limiting claudication and those with critical limb ischemia. Outcomes were analyzed by using Kaplan-Meier life-table analysis, the log-rank test for survival curves, and the one-sample t test. A Cox proportional hazard model was used to determine whether presentation and level of disease were independent predictors of outcome. RESULTS: Of the 84 patients, 54 (64.3%) were treated for claudication (34 aortoiliac occlusive disease and 20 infrainguinal disease), and 30 (35.7%) were treated for critical limb ischemia (11 aortoiliac occlusive disease and 19 infrainguinal disease). One-year results for the 54 patients with claudication were as follows: primary patency, 78.5%; limb salvage, 100%; amputation-free survival, 96.3%; survival, 96.3%; maintenance of ambulation status, 100%; and maintenance of independence, 100%. There was statistical improvement in all physical function categories, including physical function (29.4 +/- 8.9 vs 37.1 +/- 11.3; P < .0001), role-physical (32.5 +/- 11.3 vs 39.5 +/- 13.0; P = .0001), bodily pain (35.8 +/- 8.5 vs 42.9 +/- 10.9; P < .0001), and aggregate physical scoring (31.1 +/- 9.7 vs 38.1 +/- 11.5; P < .0001). One-year results for the 30 patients with critical limb ischemia were as follows: primary patency, 35.2%; limb salvage, 77.2%; amputation-free survival, 50.0%; survival, 60.0%; maintenance of ambulation status, 75.8%; and maintenance of independence, 92.8%. There was statistical improvement in bodily pain resolution (35.3 +/- 12.0 vs 46.6 +/- 12.0; P = .0009). Cox models with hazard ratios (HRs) revealed that presentation was a significant predictor for outcomes of primary patency (HR, 4.2; P= .0002), secondary patency (HR, 6.0; P < .0001), limb salvage (HR, 20.2; P = .0047), survival (HR, 10.9; P = .0002), and amputation-free survival (HR, 11.2; P < .0001). Conversely, the level of disease was predictive of outcome only for primary patency (HR, 1.8; P = .00289). CONCLUSIONS: Despite inferior reconstruction patency rates when compared with the historical results of open bypass, PTA provides excellent functional outcomes with good patient satisfaction, especially for treating claudication. These findings support a more liberal use of PTA intervention for patients with vasculogenic claudication.

Algorithms↗
PubMed2001

Use of SF-36 and SF-12 health status measures: a quantitative comparison for groups versus individual patients.

BACKGROUND: The extent to which SF-12 scores reflect SF-36 scores has not been well studied. OBJECTIVES: One purpose was to compare the sensitivity to change of the SF-36 Physical Function sub-score, and the Physical Component Summary Scores (PCS) of the SF-36 and SF-12 on patients with low back pain (LBP). A second purpose was to determine if the SF-12 could serve as a surrogate measure for the SF-36 when making decisions about individual patients. SUBJECTS: The sample consisted of 101 consecutive patients. MEASURES: SF-36 questionnaires were completed by patients at both initial and discharge examinations. SF-12 scores were calculated from the completed SF-36 questionnaires. Therapists' judgments of whether patients were judged to have returned to premorbid function served as the construct for meaningful clinical change. ANALYSIS: Receiver Operating Characteristic (ROC) curve analysis and repeated measures MANCOVA were used to assess sensitivity to change. Linear regression and 95% prediction bands described the extent to which SF-12 scores predict individual SF-36 scores. RESULTS: No significant differences were found between the ROC curve areas for the Physical Function sub-scale, the PCS-36 and PCS-12. No significant differences were found for the comparison of change scores between PF-36, PCS-36 and PCS-12 scores. CONCLUSION: The findings suggest that Physical Function sub-scores, SF-36 and SF-12 PCS scores are equally sensitive to change. SF-12 PCS scores do not adequately predict SF-36 PCS scores for individual patients. The PCS-12 should probably not be used to make judgments about the health status of individual patients with LBP.

Activities of Daily Living↗
PubMed2002

Short- and long-term outcome and health-related quality of life after severe peritonitis.

The short-form survey 36 (SF-36) is a useful and qualified instrument for measurement of health-related quality of life (HRQL) in critically ill patients. In this study we determined hospital mortality, hospital discharge mortality, and HRQL of 136 patients with severe peritonitis admitted to our hospital between January 1996 and May 1999. Hospital mortality was 46% and hospital discharge mortality 10%. The HRQL-questionnaire was answered completely by 97% of the patients who where still alive during the study period. Age significantly reduced physical functions in these patients. Patients with cancer had significant impaired physical functions in the first year, followed by significant impairment in emotion. Generally, patients who survived peritonitis and had no malignancy had an acceptable outcome when compared to individuals from a large normal population. Health-related quality of life measurements in peritonitis patients justify the high efforts in the treatment of these patients, but they do not provide a useful tool in the outcome prediction for individual patients.

Adult↗
PubMed2006

Responsiveness and clinically important differences for the WOMAC and SF-36 after total knee replacement.

OBJECTIVES: To study responsiveness and establish the minimal clinically important differences (MCIDs) and minimal detectable change (MDC) in patients undergoing total knee replacement (TKR) using the Short Form 36 (SF-36) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). METHODS: Prospective observational study in three public hospitals of all consecutive patients on waiting lists to undergo TKR intervention with diagnosis of knee osteoarthritis (OA). Patients were asked to complete before the intervention and at 6 months and 2 years afterward the SF-36 and the WOMAC health-related quality of life questionnaires (HRQoL), and additional transition questions which measured the changes in their joint at 6 months. In both questionnaires the possible range of values is from 0 to 100 points. RESULTS: In WOMAC improvement at 6 months after a TKR was between 27 (stiffness) and 31 points (pain). The SF-36 showed improvements between the 28.3 points of role physical and 2.79 of general health. From 6 months to 2 years, WOMAC improvements were between 2 and 6 points. The MCID ranged from 14.52 (stiffness) to 22.87 (pain) on the WOMAC and in the physical domains of SF-36 from 11.56 (physical function) to 16.86 (bodily pain). On the WOMAC, the MDC ranged from 13.11 (function) to 29.12 (stiffness), and on SF-36 from 19.50 (physical function) to 41.23 (social functioning). CONCLUSIONS: The MCID for TKR is around 15 on WOMAC, while with the SF-36 of at least 10 points. These values should not be considered as absolute thresholds.

Aged↗
PubMed1980

Geriatric day care and homemaker services: an experimental study.

The purpose of this study was to examine the impact of geriatric day care and homemaker services on patient outcomes. Patients were randomly assigned to receive the experimental services in three study samples. In comparing outcomes between the experimental and control groups, it was found that there were significant differences in physical functioning and activity level for the day care samples, in physical functioning and contentment level for the homemaker study sample, and in all of these outcome measures for the combined services group. Among users of the experimental services, increased use of the services was associated with improved outcomes of care. Multivariate analysis of data showed that factors other than the use of the experimental services were more effective in explaining variation in outcomes. Significant factors that affected all four outcome measures in both the day care and homemaker study were primary diagnosis, impairment prognosis, and number of inpatient hospital days.

Activities of Daily Living↗
PubMed2004

Reliability, validity, and responsiveness of the Lysholm knee scale for various chondral disorders of the knee.

BACKGROUND: The Lysholm knee scale is a condition-specific outcome measure that was originally designed to assess ligament injuries of the knee. The purpose of this study was to determine the psychometric properties of the Lysholm knee scale for various chondral disorders of the knee. METHODS: Test-retest reliability, internal consistency, content validity, criterion validity, construct validity, and responsiveness to change were determined for the Lysholm knee scale within subsets of an overall study population of 1657 patients with chondral disorders of the knee. The study population was a heterogeneous group of patients with various types of traumatic and degenerative chondral lesions, including isolated lesions and those associated with meniscal and ligament injuries. RESULTS: The overall Lysholm knee scale and six of the eight domains had acceptable test-retest reliability (intraclass correlation coefficient = 0.91) and internal consistency (Cronbach alpha = 0.65). The overall Lysholm knee scale demonstrated acceptable floor (0%) and ceiling (0.7%) effects; however, the floor effects for the domain of squatting and the ceiling effects for the domains of limp, instability, support, and locking were unacceptable (>30%). There was acceptable criterion validity with significant (p < 0.05) correlations between the overall Lysholm knee scale and the physical functioning, role-physical, and bodily pain domains of the Short Form-12 scale; the pain, stiffness, and function domains of the Western Ontario and McMaster Universities Osteoarthritis Index; and the Tegner activity scale. The overall Lysholm knee scale had acceptable construct validity, with all nine hypotheses demonstrating significance (p < 0.05), and it had acceptable responsiveness to change (effect size, 1.16; standardized response mean, 1.10), with large effects (> or = 0.80) for the domains of pain, limping, swelling, and squatting and a small effect (> or = 0.20) for the domain of instability. CONCLUSIONS: The Lysholm knee scale demonstrated overall acceptable psychometric performance for outcomes assessment of various chondral disorders of the knee, although some domains demonstrated suboptimal performance. Psychometric testing of other condition-specific knee instruments in patients with chondral disorders of the knee would be helpful to allow for comparison of psychometric properties.

Adult↗
PubMed2005

Measuring health-related quality of life in older patient populations: a review of current approaches.

The changing demographic profile of the world's population towards old age and evidence of people living for longer with less time spent in ill health highlight the importance of addressing quality-of-life (QOL) assessment issues for older people. The assessment of health-related QOL (HR-QOL) has received considerable attention in the last 2-3 decades, with a wide variety of assessment instruments available. These instruments can be either generic or disease specific, health profiles or preference based. The literature was reviewed systematically to identify studies measuring HR-QOL in older patient groups. A total of 37 studies were identified, 11 of which were randomised, controlled trials/evaluations, 14 were prospective studies that did not involve a randomised, controlled intervention, and 12 were cross-sectional studies. Studies were summarised in terms of the study aim, patient population characteristics, the instrument used to measure HR-QOL, and HR-QOL findings. A majority of studies used a generic HR-QOL instrument, the single most commonly used being the 36-Item Short-Form Health Survey. In many cases, a second disease-specific measure was used in combination with the generic measure. In a majority of studies involving interventions, significant improvements in HR-QOL were noted. In prospective studies, a negative impact of health conditions (e.g. myocardial infarction and chronic heart failure) was also identified using HR-QOL assessments. None of the studies in this review used HR-QOL measurement instruments that were old-age specific. Using instruments that are not specific to a particular age group enables comparisons to be made with other age groups, i.e. younger or middle-aged groups. However, the questionnaire items of HR-QOL instruments tend to be phrased predominantly in relation to physical function and thus may inadvertently discriminate against older persons, whose physical function is likely to be not as good as that of younger people. Particular issues in the assessment of HR-QOL in older patient populations include the persistent finding of a poor relationship between QOL and disability/disease severity, the dynamic nature of QOL, and the importance of valid proxy ratings for those unable to make decisions or communicate for themselves. It is important, therefore, that assessment of HR-QOL incorporates issues of importance to individual older people by broadening the scope of the measurement instruments, thus representing more validly the HR-QOL status of older patient groups. Future research in HR-QOL must incorporate the perspective of the individual in order to enable valid conclusions to be derived based on content that is relevant to the individual being assessed, thus informing management decisions, policy and practice more meaningfully.

Activities of Daily Living↗
PubMed2005

Ethnic variation in health-related quality of life among low-income men with prostate cancer.

OBJECTIVE: To describe and compare health-related quality of life (HRQOL) among Hispanic, African-American, and Caucasian men with localized prostate cancer. DESIGN: Observational study of low-income, ethnically diverse men with non-metastatic prostate cancer. SETTING: Statewide public assistance program in California. PARTICIPANTS: 208 men (51 Caucasian, 115 Hispanic, and 42 African-American men) with non-metastatic disease. INTERVENTIONS: Radical retropubic prostatectomy, radiation therapy, and hormonal therapy. MAIN OUTCOME MEASURES: Validated instruments measured general and disease-specific HRQOL, anxiety and fear of recurrence, spirituality, symptom distress, and self-efficacy. RESULTS: Hispanic men with prostate cancer were less educated, more often in significant relationships, and had more variable incomes compared with men of other ethnic/racial backgrounds. In univariate analyses, Caucasian men reported better physical function but less spirituality, while Hispanic men reported worse sexual function. Multivariate analysis revealed that Hispanic men had significantly worse physical function, bowel function, and bowel bother. African-American men experienced greater anxiety over recurrence. African-American and Hispanic men were more spiritual than Caucasian men. CONCLUSIONS: Greater attention to demographic variations in HRQOL may allow physicians to improve outcomes across ethnicities in low-income men with prostate cancer by offering more specialized counseling and providing referral to social support systems.

Adaptation, Psychological↗
PubMed1994

[Relationship of fundus oculi changes to declines in mental and physical health conditions among elderly living in a rural community].

The prevalence of fundus oculi changes among elderly persons living in a rural community was investigated and the relationship of those changes to the development of cerebrovascular diseases (C.V.D.), total mortality, declines in mental and physical functions was examined. The subjects consisted of 241 residents aged 70 to 75 years as of 1986, in a rural area of Yamagata prefecture, Japan. The baseline survey was carried out in 1986, and the follow-up survey was done in 1991. The results obtained were as follows: 1) The fundus oculi examination revealed that among changes observed, there were high prevalences of senile tigroid fundus, drusen, broadened light reflex, and crossing phenomenon. 2) Multivariate analysis by Hayashi's Quantification III showed that the findings of broadened light reflex, crossing phenomenon, blood pressure, and ECG were discriminated from those of senile tigroid fundus, drusen, mental function as measured by the Benton Visual Retention Test, and physical functions. It was suggested that the former fundus oculi changes were related to circulatory disease, while the latter were related to aging. 3) A severe broadened reflex predicted a high occurrence of C.V.D., and total mortality. In women, drusen had a significant direct relationship to a decline in score of the Benton Visual Retention Test. Retinal haemorrhage was related to higher total death rate in men, and women with crossing phenomenon tended to have strokes.

Aged↗
PubMed2004

Effects of extended outpatient rehabilitation after hip fracture: a randomized controlled trial.

CONTEXT: Hip fractures are common in the elderly, and despite standard rehabilitation, many patients fail to regain their prefracture ambulatory or functional status. OBJECTIVE: To determine whether extended outpatient rehabilitation that includes progressive resistance training improves physical function and reduces disability compared with low-intensity home exercise among physically frail elderly patients with hip fracture. DESIGN, SETTING, AND PATIENTS: Randomized controlled trial conducted between August 1998 and May 2003 among 90 community-dwelling women and men aged 65 years or older who had had surgical repair of a proximal femur fracture no more than 16 weeks prior and had completed standard physical therapy. INTERVENTION: Participants were randomly assigned to 6 months of either supervised physical therapy and exercise training (n = 46) or home exercise (control condition; n = 44). MAIN OUTCOME MEASURES: Primary outcome measures were total scores on a modified Physical Performance Test (PPT), the Functional Status Questionnaire physical function subscale (FSQ), and activities of daily living scales. Secondary outcome measures were standardized measures of skeletal muscle strength, gait, balance, quality of life, and body composition. Participants were evaluated at baseline, 3 months, and 6 months. RESULTS: Changes over time in the PPT and FSQ scores favored the physical therapy group (P =.003 and P =.01, respectively). Mean change (SD) in PPT score for physical therapy was +6.5 (5.5) points (95% confidence interval [CI], 4.6-8.3), and for the control condition was +2.5 (3.7) points (95% CI, 1.4-3.6 points). Mean change (SD) in FSQ score for physical therapy was +5.2 (5.4) points (95% CI, 3.5-6.9) and for the control condition was +2.9 (3.8) points (95% CI, 1.7-4.0). Physical therapy also had significantly greater improvements than the control condition in measures of muscle strength, walking speed, balance, and perceived health but not bone mineral density or fat-free mass. CONCLUSION: In community-dwelling frail elderly patients with hip fracture, 6 months of extended outpatient rehabilitation that includes progressive resistance training can improve physical function and quality of life and reduce disability compared with low-intensity home exercise.

Activities of Daily Living↗
PubMed1997

Validating the SF-36 health survey questionnaire in patients with psoriatic arthritis.

OBJECTIVE: To assess the reliability and validity of the SF-36 in patients with psoriatic arthritis (PsA). METHODS: The SF-36 was administered to all patients attending the University of Toronto Psoriatic Arthritis Clinic between January and December 1994. Clinical and radiological assessments were performed during the clinic visits. RESULTS: We studied 113 patients, 43 women and 70 men, with a mean age of 50.5 years and a mean arthritis duration of 14.2 years. The reliability of the SF-36 was high, with the Cronbach alpha coefficient exceeding 0.90 for all the 8 health scales. The SF-36 was able to detect meaningful differences in health status between patients with PsA and individuals from the general population. As predicted, patients with PsA reported substantially lower scores on the physical functioning, role limitations due to physical problems, and pain scales. They also reported significantly lower scores on the role limitations due to emotional problems and general health perception scale. In general all scales were moderately to highly correlated with measures of function and pain (r = 0.33-0.67), while the physical functioning, pain, and vitality scales were also moderately correlated with disease activity (r = 0.34-0.42). With one exception the scales were unrelated to disease severity. CONCLUSION: The SF-36 questionnaire is reliable and valid for use in PsA, supporting its use as an adjunct outcome measure for clinical trials in PsA. Because the SF-36 can be used to compare health status across different patient populations, its application can also help to clarify the disease burden associated with PsA.

Adult↗
PubMed2004

An evaluation of quality of life of mothers of children with cerebral palsy.

PURPOSE: To evaluate the quality of life of mothers with children suffering from cerebral palsy compared with those who have children with minor health problems. METHOD: Forty mothers with a child suffering from cerebral palsy and 44 mothers with a child suffering from minor health problems participated in a comparative study. The Turkish version of the Medical Outcomes 36-Item Short Form Health Survey (SF-36) was used to assess a mother's quality of life. The severity of a child's motor disability was assessed using the Gross Motor Function Classification System (GMFCS). RESULTS: With the exception of the SF-36 physical functioning subscale, the mean scores on the SF-36 subscales were significantly lower in mothers of children with CP than those of the comparison group. The quality of life scores of mothers were significantly correlated with the severity of a child's motor disability (except physical functioning subscale). Significant correlations were found between GMFCS and the role physical; vitality; role emotional; and mental health subscales of the SF-36. CONCLUSIONS: The quality of life profile of mothers of children with cerebral palsy is different from those who have a child with minor health problems. Different coping strategies and psychosocial programmes must be designed and implemented to decrease the burden of care.

Adult↗
PubMed2006

Relationship of patient and medical characteristics to health status in children and adolescents after the Fontan procedure.

BACKGROUND: After the Fontan procedure, patients are at risk for suboptimal health status related to their complex healthcare experience, physiological limitations, medical complications, and guarded long-term prognosis. METHODS AND RESULTS: In the Pediatric Heart Network cross-sectional study of Fontan survivors 6 to 18 years of age, parents completed the Child Health Questionnaire, and scores were related in multivariable analysis to patient and medical characteristics obtained from medical record review. For 537 patients (mean age at study, 11.9 years; 60% male) with a median age at Fontan of 2.8 years (range, 0.7 to 14.6 years), parent-reported patient morbidities included deficits in vision in 33%, speech in 27%, and hearing in 7%, as well as problems with attention in 46%, learning in 43%, development in 24%, behavior in 23%, anxiety in 17%, and depression in 8%. Child Health Questionnaire summary scores were significantly lower than the US population sample for Physical Functioning (mean Z score, -0.47+/-1.19; P<0.001) and Psychosocial Functioning (-0.28+/-1.08; P<0.001). Parent-reported medical conditions and long-term and current medical problems explained the greatest amount of variation in the Physical Functioning scores. Parent-reported patient conditions, including behavior, learning, anxiety, and attention problems and depression, explained the greatest amount of variation in the Psychosocial Functioning scores. Lower family income had a negative impact on both Physical and Psychosocial Functioning. CONCLUSIONS: There are deficits in health status in children and adolescents after the Fontan procedure. Strategies to address this problem might emphasize coordinated and effective prevention, detection, and management of noncardiac and psychosocial conditions, as well as specific targeting of patients from low-income households.

Adolescent↗
PubMed2006

Performance measures provide assessments of pain and function in people with advanced osteoarthritis of the hip or knee.

BACKGROUND AND PURPOSE: Pain and physical function are core outcome measures for people with osteoarthritis, and self-report questionnaires have been the preferred assessment method. There is evidence suggesting that self-reports of physical function represent what people experience when performing activities rather than their ability to perform activities. The purpose of this study was to examine the factorial validity of performance-specific assessments of pain and function. SUBJECTS: The sample consisted of 177 participants who had osteoarthritis of the hip (n=81) or knee (n=96) and who were awaiting total joint arthroplasty. METHODS: Through a cross-sectional design, participants performed 4 performance activities (self-paced walk test, stair test, Timed "Up & Go" Test, and Six-Minute Walk Test). OUTCOMES: were time or distance (function) and pain ratings obtained immediately after each activity. The authors conceptualized 2 correlated factors, with pain items loading uniquely on 1 factor and functional items loading on the second factor, and uncorrelated error terms. Confirmatory factor analysis was applied. RESULTS: Initial analysis yielded results consistent with the conceptualized model in this study with the exception of a nonzero correlation between the stair pain and function error terms. Dropping the stair test provided results consistent with the conceptualized model. DISCUSSION AND CONCLUSION: Given the limitations of self-report alone as a method of obtaining reasonably distinct assessments of pain and function, the extent to which performance-specific assessments could accomplish this goal was examined in this study. It was found that collectively the walk test, Timed "Up & Go" Test, and Six-Minute Walk Test yielded 2 factors consistent with the health concepts of pain and function. The authors believe that the application of these tests may provide clinicians and clinical researchers with more distinct impressions of pain and function that complement information from self-report measures.

Aged↗
PubMed1996

Functional and physical interactions between partial molecules of STE6, a yeast ATP-binding cassette protein.

The Saccharomyces cerevisiae a-factor transporter, STE6, is a member of the ATP binding cassette (ABC) transporter superfamily. ABC proteins consist of four modular units that comprise two membrane-spanning domains (MSDs) and two nucleotide-binding domains (NBDs). Like many ABC proteins, STE6 contains these four domains in a single polypeptide; certain other ABC proteins are encoded as pairs of "half-molecules" or are further subdivided. Our previous studies demonstrated that STE6 can be expressed as two half-molecules that are functional when co-expressed. Here we dissect the interactions between modules of STE6 in greater detail. We show by co-immunoprecipitation that STE6 half-molecules interact physically, supporting the view that they co-assemble in vivo to form a functional transporter. We also demonstrate a physical interaction between a STE6 half-molecule and full-length STE6; such complexes appear to be functional, based on the striking finding that the defective activity of full-length STE6 mutated in one of its NBDs can be corrected by co-expression of the corresponding "wild-type" half-molecule. We also show that a quarter-molecule consisting solely of the N-terminal MSD of STE6 can interact physically and functionally with a C-terminal three-quarter molecule of STE6, indicating that information directing the assembly of STE6 from partial molecules is contained, at least in part, within its membrane spans.

ATP-Binding Cassette Transporters↗