Sarcoplasmic reticulum calcium ATPase 2a (SERCA2a)

Sarcoplasmic reticulum calcium ATPase 2a (SERCA2a) is an essential membrane-bound enzyme found predominantly in cardiac muscle cells. It actively transports two Ca²⁺ ions from the cytoplasm into the lumen of the sarcoplasmic reticulum during muscle relaxation at the expense of one molecule of ATP. This process is critical for maintaining low resting cytosolic Ca²⁺ concentrations, enabling proper excitation-contraction coupling, regulating myocardial contractility, and ensuring efficient contraction-relaxation cycles within cardiomyocytes. The functional integrity and expression level of SERCA2a are tightly regulated by small proteins such as phospholamban; dysregulation contributes significantly to various forms of heart disease including systolic dysfunction seen in chronic heart failure. Pharmacological modulation—either inhibition or enhancement—of this pump has been explored both experimentally and clinically as a strategy for treating cardiovascular diseases.

Other names

SERCA2aSarco(endo)plasmic reticulum Ca²⁺-ATPase 2aATP2A2 (gene name)Cardiac sarcoplasmic reticulum Ca²⁺ pump

Drugs such as thapsigargin and cyclopiazonic acid inhibit the enzyme by blocking its ability to hydrolyze ATP and transport Ca²⁺ ions into the SR, leading to increased cytosolic Ca²⁺ levels. Some investigational therapies aim to enhance SERCA activity or expression as a means of improving cardiac function in heart failure.