question: Is Sarcolipin a regulatory/inhibitory protein of the Calcium ATPase SERCA?
answer: Sarcolipin (SLN) is a 3 kD membrane protein found in sarcoplasmic reticulum (SR) and it is a newly identified regulator of the sarco/endoplasmic reticulum Ca(2+)-ATPase (Serca) pump.  SLN inhibits sarcoplasmic reticulum Ca(2+) ATPase (SERCA) activity and reduces its affinity of Ca(2+), resulting in dysfunction of myocardial contraction and heart failure. Sarcolipin is a key regulator of SERCA2a in atria.