Fig. 1Proposed mechanism to show how sarcolipin (SLN)/sarcoendoplasmic reticulum calcium APTase (SERCA) interaction affects muscle metabolism. SERCA uses adenosine triphosphate (ATP) hydrolysis to actively transport Ca2+ from the cytosol into the sarcoplasmic reticulum lumen. SLN and Ca2+ bind competitively to SERCA during Ca2+ transport. SLN binding to SERCA does not inhibit ATP hydrolysis but prevents Ca2+ transport by a mechanism named uncoupling, where Ca2+ slips back into cytosol. Uncoupling of SERCA leads to futile cycling of the SERCA pump resulting in increased ATP hydrolysis/heat production; thus, creating energy demand. Uncoupling of SERCA increases cytosolic Ca2+ acutely, thereby promoting Ca2+ entry into mitochondria matrix activating the oxidative metabolism and ATP synthesis. RyR1, ryanodine receptor 1; ADP, adenosine diphosphate; Pi, inorganic phosphate.