Biomedical subjects

Kevin C Facemyer

Publications and source records attributed to Kevin C Facemyer.

3 recordsLinked to original sources

PubMed2006

The N-terminal lobes of both regulatory light chains interact with the tail domain in the 10 S-inhibited conformation of smooth muscle myosin.

In the presence of ATP, unphosphorylated smooth muscle myosin can form a catalytically inactive monomer that sediments at 10 Svedbergs (10 S). The tail of 10 S bends into thirds and interacts with the regulatory domain. ADP-P(i) is "trapped" at the active site, and consequently the ATPase activity is extremely low. We are interested in the structural basis for maintenance of this off state. Our prior photocross-linking work with 10 S showed that tail residues 1554-1583 are proximal to position 108 in the C-terminal lobe of one of the two regulatory light chains ( Olney, J. J., Sellers, J. R., and Cremo, C. R. (1996) J. Biol. Chem. 271, 20375-20384 ). These data suggested that the tail interacts with only one of the two regulatory light chains. Here we present data, using a photocross-linker on position 59 on the N-terminal lobe of the regulatory light chain (RLC), demonstrating that both regulatory light chains of a single molecule can cross-link to the light meromyosin portion of the tail. Mass spectrometric data show four specific cross-linked regions spanning residues 1428-1571 in the light meromyosin portion of the tail, consistent with cross-linking two RLC to one light meromyosin. In addition, we find that position 59 can cross-link internally to residues 42-45 within the same RLC subunit. The internal cross-link only forms in 10 S and not in unphosphorylated heavy meromyosin (lacking the light meromyosin), suggesting a structural rearrangement within the RLC attributed to the interaction of the tail with the head.

Amino Acid Sequence↗

PubMed2006

Web-based learning versus standardized patients for teaching clinical diagnosis: a randomized, controlled, crossover trial.

BACKGROUND: Little evidence exists to guide the selection of methods for teaching clinical diagnosis. PURPOSE: To compare the efficacy, student preference, and cost of a Web-based (WB) program versus a standardized patient (SP) encounter for teaching clinical diagnosis skills to 2nd-year medical students. METHODS: Randomized, controlled, crossover study comparing WB versus SP-based teaching for the clinical diagnosis of abdominal pain and headache. Outcome measures were performance on a 2-case SP examination (scored on the basis of a checklist completed by a faculty observer and an objective score on a postencounter subjective-objective assessment plan [SOAP] note), format preferences as assessed by end-of-course evaluations, and cost. RESULTS: Thirty students consented to participate. WB and SP training produced similar scores on both the Abdominal Pain checklist (66% vs. 62%; p = .17) and Headache checklist (56% vs. 63%; p = .07). WB training produced a higher score on the Abdominal Pain SOAP note (69% vs. 47%; p = .006), but not the Headache SOAP note (69% vs. 67%; p = .85). Students rated the SP format higher than the WB format on all 7 preference measures. Start-up costs were estimated at 2,190 dollars for the SP format and 2,250 dollars for the WB format. Ongoing costs per case per student were estimated to be 45 dollars for the SP format and 30 dollars for the WB format. CONCLUSIONS: WB and SP learning outcomes were comparable, but students preferred the SP format. Start-up costs were comparable, but the ongoing costs of the WB format were less expensive, suggesting that WB teaching may be a viable strategy.

Algorithms↗

PubMed2002

Structural model of the regulatory domain of smooth muscle heavy meromyosin.

The goal of this study was to provide structural information about the regulatory domains of double-headed smooth muscle heavy meromyosin, including the N terminus of the regulatory light chain, in both the phosphorylated and unphosphorylated states. We extended our previous photo-cross-linking studies (Wu, X., Clack, B. A., Zhi, G., Stull, J. T., and Cremo, C. R. (1999) J. Biol. Chem. 274, 20328-20335) to determine regions of the regulatory light chain that are cross-linked by a cross-linker attached to Cys(108) on the partner regulatory light chain. For this purpose, we have synthesized two new biotinylated sulfhydryl reactive photo-cross-linking reagents, benzophenone, 4-(N-iodoacetamido)-4'-(N-biotinylamido) and benzophenone, 4-(N-maleimido)-4'-(N-biotinylamido). Cross-linked peptides were purified by avidin affinity chromatography and characterized by Edman sequencing and mass spectrometry. Labeled Cys(108) from one regulatory light chain cross-linked to (71)GMMSEAPGPIN(81), a loop in the N-terminal half of the regulatory light chain, and to (4)RAKAKTTKKRPQR(16), a region for which there is no atomic resolution data. Both cross-links were to the partner regulatory light chain and occurred in unphosphorylated but not phosphorylated heavy meromyosin. Using these data, data from our previous study, and atomic coordinates from various myosin isoforms, we have constructed a structural model of the regulatory domain in an unphosphorylated double-headed molecule that predicts the general location of the N terminus. The implications for the structural basis of the phosphorylation-mediated regulatory mechanism are discussed.

Amino Acid Sequence↗