Solubilization and Reconstitution of the Calcium Release Channel of Skeletal Sarcoplasmic Reticulum

Abstract

Fragmented heavy sarcoplasmic reticulum was solubilized by cholate, and proteins were subsequently fractionated by using diethylaminoethyl-cellulose (DEAE-cellu-lose) column chromatography. A fraction was collected in which proteins with molecular weights between 31,000 and 45,000 u were major components. This fraction, when incorporated into Ca²⁺-loaded liposomes, facilitated the Ca²⁺ efflux. The rate of efflux was regulated by the external Ca²⁺ concentration, reaching a maximum at 3 μ-M Ca²⁺. The Ca²⁺ efflux was suppressed by Mg²⁺.