Calmodulin is intrinsically LESS effective than troponin C in activating skeletal muscle contraction

FEBS Letters

George, Samuel E.¹  Schachat, Fred³  Brandt, Philip W.² 

[1] Department of Medicine and Pharmacology, Duke University Medical Center, Durham, NC 27710, USA;Department of Anatomy and Cell Biology, Columbia University School of Medicine, New York, NY 10032, USA;Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA

关键词: Calmodulin;    Troponin C;    Skeletal muscle;    Muscle contraction;   

DOI  :  10.1016/0014-5793(94)01016-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Calmodulin (CaM) and troponin C (TnC) are evolutionarily and structurally homologous, yet they are not functionally interchangeable. In particular, CaM cannot effectively substitute for TnC as an activator of skeletal muscle contraction. To determine if this is a consequence of CaM's weak association with troponin T and I or the result of a more fundamental mechanistic defect, we have used CaM and a CaM[TnC] chimera, CaM[3,4 TnC], that stably associates with the thin filament. Replacement of TnC with CaM or CaM[3,4 TnC] reveals that CaM-like molecules reduce the Ca²⁺-sensitivity and cooperativity of activation, as well as the maximal Ca²⁺-activated tension. These observations indicate that CaM-like molecules are unable to continuously maintain the activated state of the thin filament.

【 授权许可】

Unknown