Ca²⁺ Dependent Formation/Collapse of Cylindrical Ca²⁺-ATPase Crystals in Scallop Sarcoplasmic Reticulum (SR) Vesicles: A Possible Dynamic Role of SR in Regulation of Muscle Contraction.

ABSTRACT: [Ca²⁺]-dependent crystallization of the Ca²⁺-ATPase molecules in sarcoplasmic reticulum (SR) vesicles isolated from scallop striated muscle elongated the vesicles in the absence of ATP, and ATP stabilized the crystals. Here, to determine the [Ca²⁺]-dependence of vesicle elongation in the presence of ATP, SR vesicles in various [Ca²⁺] environments were imaged using negative stain electron microscopy. The images obtained revealed the following phenomena. (i) Crystal-containing elongated vesicles appeared at ≤1.4 µM Ca²⁺ and almost disappeared at ≥18 µM Ca²⁺, where ATPase activity reaches its maximum. (ii) At ≥18 µM Ca²⁺, almost all SR vesicles were in the round form and covered by tightly clustered ATPase crystal pa

SUBMITTER: Nakamura J 

PROVIDER: S-EPMC10139091 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature