S100A1 modulates skeletal muscle contraction by desensitizing calcium activation of isometric tension, stiffness and ATPase.
S100, a subfamily of the EF-hand type calcium sensing proteins, is implicated in many cellular functions including muscle contractility. Two isoforms, S100A1 and S100B, at 2-10 microM significantly inhibit active tension, stiffness and ATPase of skinned single rabbit psoas muscle fibers at sub-maximal (pCa approximately 6.1-5.6), but not at maximal levels of activation (pCa 4.0). S100A1 is a more potent inhibitor than S100B. Hill analysis of the ATPase-pCa and tension-pCa curves indicates that these proteins reduce calcium sensitivity and enhance the cooperativity toward calcium. We propose S100A1, and perhaps S100B, are viable candidates as physiological modulators of muscle contraction.
Adhikari
B B
BB
Laboratory of Physical Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Building 6, Room 408, Bethesda, MD 20892, USA.
Wang
K
K
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000378:metabolism* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism; D009129:Muscle Tonus / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism / Q000494:pharmacology; D011817:Rabbits; D009418:S100 Proteins
D002135:Calcium-Binding Proteins; D020033:Protein Isoforms; D009418:S100 Proteins; C110294:S100A1 protein; D000251:Adenosine Triphosphatases; D002118:Calcium