Figure 1.

The pathways of heat generation in muscle cells. Non-shivering thermogenesis (NST) in muscle cells is activated by the binding of the peptide sarcolipin (SLN) to the Ca²⁺ ATPase (SERCA), the transmembrane Ca²⁺ pump located in the sarcoplasmatic reticulum (SR) membrane. SLN causes Ca²⁺-slippage with the sole purpose of heat generation. Heat is also generated by mitochondria, the sodium-potassium pump, and myofibril contraction. For more details see text. Modified after Herpin et al. (2002).