The overall goals of our studies are to advance the understanding of the cross-bridge mechanisms in muscular contraction, and to provide insights into the relationships between the biochemical and mechanical events in the cross-bridge cycle. To achieve the major goals chemically treated skinned hamster fiber preparations are utilized having certain moities extracted from the contractile apparatus and then reconstituted with either homologous proteins of the same tissue or the heterologous moities such as from cardiac muscle or from other species. In addition the intact fiber preparation from frog muscle is used in selected experiments to duplicate conditions closer to in vivo. To study properties of the cross-bridge mechanisms, the experiments on control fibers are carried out at various ionic strengths which helps isolate the individual states of cross-bridges that are representative of the configurations during the normal cross-bridge cycle.
The specific aims are to (1) identify the steps in the cycle that are regulated by Ca2+, (2) specify the roles of the regulatory proteins with special emphasis on the identification and characterization of presumably a new cofactor in muscle regulation, and (3) study of the rate limiting steps in the cross-bridge cycle of Vmax and force development. The study is also made of (4) the modification of the cross-bridge kinetics by internal loads that are increased by the compressions of the filament lattice and specifically examines whether the origin of filamentory interactions during such compressions is from particular cross-bridge configurations. The implications of these cross-bridge configurations for the normal contraction and relaxation is examined. In addition (5) the observations on the compartmentalizations of calmodulin in muscle fiber are extended to examine the location of CaM in the fibers by using the immunological techniques combined with EM. The specific roles of the various Ca2+ binding sites in the different aspects of the activation of cross-bridges for contraction are also examined by using different Ca-binding proteins. The results would advance the understanding of the regulatory mechanisms in the contraction process as well as provide new insights into the cross-bridge mechanisms.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
2R01AR033736-04A1
Application #
3156641
Study Section
Cardiovascular Study Section (CVA)
Project Start
1984-12-01
Project End
1991-06-30
Budget Start
1988-07-01
Budget End
1989-06-30
Support Year
4
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Albert Einstein College of Medicine
Department
Type
Schools of Medicine
DUNS #
009095365
City
Bronx
State
NY
Country
United States
Zip Code
10461
Akella, A B; Su, H; Sonnenblick, E H et al. (1997) The cardiac troponin C isoform and the length dependence of Ca2+ sensitivity of tension in myocardium. J Mol Cell Cardiol 29:381-9
Ding, X L; Akella, A B; Sonnenblick, E H et al. (1996) Molecular basis of depression of Ca2+ sensitivity of tension by acid pH in cardiac muscles of the mouse and the rat. J Card Fail 2:319-26
Akella, A B; Sonnenblick, E H; Gulati, J (1996) Alterations in myocardial contractile proteins in diabetes mellitus. Coron Artery Dis 7:124-32
Ding, X L; Akella, A B; Gulati, J (1995) Contributions of troponin I and troponin C to the acidic pH-induced depression of contractile Ca2+ sensitivity in cardiotrabeculae. Biochemistry 34:2309-16
Gulati, J; Akella, A B; Su, H et al. (1995) Functional role of arginine-11 in the N-terminal helix of skeletal troponin C: combined mutagenesis and molecular dynamics investigation. Biochemistry 34:7348-55
Rao, V G; Akella, A B; Su, H et al. (1995) Molecular mobility of the Ca(2+)-deficient EF-hand of cardiac troponin C as revealed by fluorescence polarization of genetically inserted tryptophan. Biochemistry 34:562-8
Akella, A B; Ding, X L; Cheng, R et al. (1995) Diminished Ca2+ sensitivity of skinned cardiac muscle contractility coincident with troponin T-band shifts in the diabetic rat. Circ Res 76:600-6
Ding, X L; Akella, A B; Su, H et al. (1994) The role of glycine (residue 89) in the central helix of EF-hand protein troponin-C exposed following amino-terminal alpha-helix deletion. Protein Sci 3:2089-96
Keleti, D; Rao, V G; Su, H et al. (1994) Disparate contributions of Tyr10 and Tyr109 to fluorescence intensity of rabbit skeletal muscle troponin C identified using a genetically engineered mutant. FEBS Lett 354:135-9
Gulati, J; Rao, V G (1994) The cardiac Ca(2+)-deficient EF-hand governs the phenotype of the cardiac-skeletal TnC-chimera in solution by Sr(2+)-induced tryptophan fluorescence emission. Biochemistry 33:9052-6

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