Purification and characterization of calsequestrin from canine cardiac sarcoplasmic reticulum and identification of the 53,000 dalton glycoprotein.

Abstract

Cardiac calsequestrin was extracted from canine cardiac sarcoplasmic reticulum vesicles with Nonidet P-40 and purified by precipitation with calcium phosphate followed by fractionation on DEAE-cellulose.It bound 300 nmol of Ca2+/mg of protein and glutamic and aspartic acid constituted approximately 32% of the amino acid residues in the protein.The apparent molecular weight of canine cardiac calsequestrin was 55,000 when measured in alkaline sodium dodecyl sulfate gels and 44,000 when measured in neutral sodium dodecyl sulfate gels.Cardiac calsequestrin, like skeletal muscle calsequestrin, stains blue with "Stains-all" and is therefore the 55,000 dalton protein which Jones and Cala ((1981)