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Biomedical subjects

M Killeen

Publications and source records attributed to M Killeen.

12 recordsLinked to original sources
PubMed2001

Netrin stimulates tyrosine phosphorylation of the UNC-5 family of netrin receptors and induces Shp2 binding to the RCM cytodomain.

Caenorhabditis elegans UNC-5 and its mammalian homologues such as RCM are receptors for the secreted axon guidance cue UNC-6/netrin and are required to mediate the repulsive effects of UNC-6/netrin on growth cones. We find that C. elegans UNC-5 and mouse RCM are phosphorylated on tyrosine in vivo. C. elegans UNC-5 tyrosine phosphorylation is reduced in unc-6 null mutants, and RCM tyrosine phosphorylation is induced by netrin-1 in transfected HEK-293 cells, demonstrating that phosphorylation of UNC-5 proteins is enhanced by UNC-6/netrin stimulation in both worms and mammalian cells. An activated Src tyrosine kinase induces phosphorylation of RCM at multiple cytoplasmic tyrosine residues creating potential binding sites for cytoplasmic signaling proteins. Indeed, the NH2-terminal SH2 domain of the Shp2 tyrosine phosphatase bound specifically to a Tyr(568) RCM phosphopeptide. Furthermore, Shp2 associated with RCM in a netrin-dependent manner in transfected cells, and co-immunoprecipitated with RCM from an embryonic mouse brain lysate. A Y568F mutant RCM receptor failed to bind Shp2 and was more highly phosphorylated on tyrosine than the wild type receptor. These results suggest that netrin-stimulated phosphorylation of RCM Tyr(568) recruits Shp2 to the cell membrane where it can potentially modify RCM phosphorylation and function.

Amino Acid Sequence↗
PubMed1992

Recombinant TBP, transcription factor IIB, and RAP30 are sufficient for promoter recognition by mammalian RNA polymerase II.

Initiation of transcription by RNA polymerase II is a complex, multistep process which requires several accessory factors in addition to the polymerase itself. A critical event in transcription initiation is the specific association of RNA polymerase II with promoter DNA. In this report we show that three eukaryotic polypeptides, produced in Escherichia coli and purified to near homogeneity, constitute a minimal set of general transcription factors both necessary and sufficient for specific and stable promoter binding by RNA polymerase II. These polypeptides are the yeast TATA box binding protein TBP, the human general initiation factor TFIIB, and human RAP30, the small subunit of RAP30/74 (or transcription factor IIF). Formation of the polymerase-containing complex required only the TATA box, and not the initiator element (Inr), of the adenovirus major late promoter which was used in these experiments.

Base Sequence↗
PubMed1992

Identification of three mammalian proteins that bind to the yeast TATA box protein TFIID.

The TATA box binding transcription factor TFIID of S. cerevisiae was used as a ligand for affinity chromatography. Polypeptides that bind specifically to yeast TFIID (TFIID-associated proteins, DAPs) were purified from human HeLa (heDAPs) and calf thymus (ctDAPs) whole cell extracts. Both heDAP and ctDAP fractions altered the binding of TFIID to the TATA element, and substituted for the TFIIA transcription activity in a reconstituted in vitro system. The heDAP fraction also behaved like TFIIA in its ability to form a promoter-TFIID-TFIIA complex and to recruit TFIIB to such a complex. The interaction of DAPs with TFIID can confer heat-resistance (47 degrees C) on recombinant yeast or human TFIID. SDS-PAGE analysis revealed that three polypeptides from HeLa extracts specifically bound to yTFIID columns (heDAP35, heDAP21, and heDAP12). These data suggest that a multi-subunit transcription factor with the properties of TFIIA can bind to TFIID in the absence of DNA.

Base Sequence↗
PubMed1991

The small subunit of transcription factor IIF recruits RNA polymerase II into the preinitiation complex.

We found that transcription factor IIF mediates the association of RNA polymerase II with promoter sequences containing transcription factors IID, IIB, and IIA (DAB complex). The resulting DNA-protein complex contained RNA polymerase II and the two subunits of transcription factor IIF (RAP 30 and RAP 74). Cloned human RAP 30 was sufficient for the recruitment of RNA polymerase II to the DAB complex. This ability of RAP 30 to recruit RNA polymerase to a promoter is also a characteristic of sigma factors in prokaryotes.

Adenoviridae↗
PubMed1990

The influence of stress and coping on family caregivers' perceptions of health.

Family members are increasingly assuming a caregiving role for their frail elders. This role, which is added to their other responsibilities, competes for time and attention and may generate stressful situations. Previous research established that stress may have both adaptive and maladaptive effects on individuals. This study examines the extent to which caregivers perceive their situations as stressful, how they cope, and the associated influences of stress and coping on perceptions of their own health. The aim is to identify stressful aspects of caregiving and ways of coping that may be maladaptive for caregivers, placing them at risk for illness and disease.

Adaptation, Psychological↗
PubMed1988

RAP30/74: a general initiation factor that binds to RNA polymerase II.

We have previously shown by affinity chromatography that RAP30 and RAP74 are the mammalian proteins that have the highest affinity for RNA polymerase II. Here we show that RAP30 binds to RAP74 and that the RAP30-RAP74 complex (RAP30/74) is required for accurate initiation by RNA polymerase II. RAP30/74 is required for accurate transcription from the following promoters: the adenovirus major late promoter, the long terminal repeat of human immunodeficiency virus, P2 of the human c-myc gene, the mouse beta maj-globin promoter (all of which have TATA boxes), and the mouse dihydrofolate reductase promoter (which lacks a TATA box). RAP30/74 is not required for initiation by RNA polymerase III at the adenovirus virus-associated RNA promoters. Therefore, RAP30/74 is a general initiation factor that binds to RNA polymerase II.

Carrier Proteins↗
PubMedDate not supplied

Health promotion practices of family caregivers.

This study was conducted to assess the relationship of length of time in the caregiving role, amount of care provided, participation in health promotion activities, selected demographic variables, and caregivers' perceptions of their own health. Subjects were 120 adults who were primary caregivers for a frail elder at home. Data were analyzed using frequency statistics, correlational statistics, and multiple regression analysis. Overall, subjects had at least a high school education and were Caucasian. Perceptions of health were negatively associated with amount of care rendered by caregivers, but were not associated with length of time in the caregiving role. Participation in health promotion activities was associated with positive assessments of health. Daughters were most frequently caregivers, but least likely to participate in health promotion activities. Regression analysis revealed that two variables, amount of care given and participation in health promotion activities, accounted for 13% of the variance in perceptions of health; three variables, age, education, and time in the caregiving role, accounted for 18% of the variance in participation in health promotion activities.

Adult↗