Interaction of a Sarcolipin Pentamer and Monomer with the Sarcoplasmic Reticulum Calcium Pump, SERCA (Biophysical Journal)

The sequential rise and fall of cytosolic calcium underlies the contraction-relaxation cycle of muscle cells. Whereas contraction is initiated by the release of calcium from the sarcoplasmic reticulum, muscle relaxation involves the active transport of calcium back into the sarcoplasmic reticulum. This reuptake of calcium is catalyzed by the sarcoendoplasmic reticulum Ca2+-ATPase (SERCA), which plays a lead role in muscle contractility. The activity of SERCA is regulated by small membrane protein subunits, the most well-known being phospholamban (PLN) and sarcolipin (SLN).