Calsequestrin is the major calcium storage protein of the sarcoplasmic reticulum. Intraluminar Ca2+ binds to calsequestrin during diastole to prevent Ca2+ precipitation and to lower its free ionic concentration to facilitate efficient storage. During systole, Calsequestrin coordinately releases ~40-50 Ca2+ ions per molecule for each contraction-relaxation cycle by an uncertain mechanism. Calsequestrin has been shown to be of major importance in the regulation of cardiac excitation-contraction coupling. Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile ddH2O, carrier protein (0.1% HSA or BSA. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
