Module 5: Figure SERCA pump cycle
The sarco/endo-plasmic reticulum Ca2+-ATPase (SERCA) pump cycle.
The pump cycle consists of a series of biochemical reactions during which the pump switches between two major conformational states: an E1 state when the Ca2+-binding site faces the cytoplasm, and an E2 state where the binding sites have switched to the opposite side and Ca2+ is released to the lumen. During each cycle, two Ca2+ ions are pumped for each ATP hydrolysed. This switch between the E1 and E2 states represents one cycle, and this occurs at a frequency of about 150 reactions/s. The way in which ATP powers each pump cycle is described in the text. An animated version of this figure is available.