Characterization of the Ca2+‐switch in skeletal and cardiac muscles

FEBS Letters

Lehman, W.¹  Babu, A.²  Gulati, J.² 

[1] Boston University School of Medicine, Boston, MA 02118, USA;Albert Einstein College of Medicine, Bronx, NY 10461 USA

关键词: Troponin C;    Calmodulin;    Parvalbumin;    Oncomodulin;   

DOI  :  10.1016/0014-5793(89)81450-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

To determine the significance of the global structure of the regulatory proteins in the mechanism of the Ca²⁺-switch in cardiac and skeletal muscle contractions, the properties of a family of Ca²⁺-binding proteins with 4 or 3 EF-hand motifs have been studied with desensitized skinned fiber preparations. Proteins with 4 EF hands (such as troponins C - TnCs) are dumb-bell shaped, those with 3 EF hands (parvalbumin) being ellipsoidal. The number of active sites varied between four and two. We find that the ability to anchor in the fiber is limited to proteins with 4 EF hands and, at least, two active Ca²⁺-binding sites, one each in the N- and C-termini. The results suggest that the dumb-bell shaped global structure is critical for the switching action in muscular contraction, and a trigger site in the N-terminus and a structural site in the C-terminus need to be active in order to regulate contractility.

【 授权许可】

Unknown