Sarcoplasmic reticulum release channels from frog skeletal muscle display two types of calcium dependence

FEBS Letters

Marengo, Juan José¹  Bull, Ricardo¹ 

[1] Departamento de Fisiologia y Biofisica, Facultad de Medicina, Universidad de Chile, Casilla 70005, Correo 7, Santiago, Chile

关键词: Sarcoplasmic reticulum;    Ca2+ channel;    Ca2+ release;    Ca2+ regulation;    Skeletal muscle;   

DOI  :  10.1016/0014-5793(93)80341-Q

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Calcium channels derived from sarcoplasmic reticulum of frog skeletal muscle were fused with planar lipid bilayers. Fractional open times displayed two types of calcium dependence: (i) blockable channels showed a bell-shaped calcium dependence with an activation constant of 4.5 μM, a Hill coefficient for activation of 1.46 and a blocking constant of 226 μM, and (ii) non-blockable channels displayed a sigmoidal calcium dependence with an activation constant of 1.1 μM and a Hill coefficient of 1.42; no blocking effect was seen with calcium up to 0.5 mM. These two types of calcium dependence may underlie the coexistence of two different pathways for calcium release in frog skeletal muscle.

【 授权许可】

Unknown