question: Which is the main regulatory molecule of SERCA2A function in the cardiac muscle?
answer: SERCA2a activity is regulated by phosphorylation of another SR protein, Phospholamban (PLN). Phospholamban (PLB) inhibits the activity of SERCA2a, the Ca(2+)-ATPase in cardiac sarcoplasmic reticulum, by decreasing the apparent affinity of the enzyme for Ca(2+).