Sarcolipin Makes Heat, but Is It Adaptive Thermogenesis?

A regulatory protein (sarcolipin or SLN) bound to SERCA pumps in the sarcoplasmic reticulum (SR) of cardiac and skeletal muscle has been shown to increase heat production in vitro. Here, we review recent work in this area, assess the potential of in vivo heat generation by this mechanism, and advocate that a comparative approach is the best path toward resolving many outstanding questions on the physiological function, regulation, and evolution of SLN.