A focus on extracellular Ca entry into skeletal muscle.

The main task of skeletal muscle is contraction and relaxation for body movement and posture maintenance. During contraction and relaxation, Ca in the cytosol has a critical role in activating and deactivating a series of contractile proteins. In skeletal muscle, the cytosolic Ca level is mainly determined by Ca movements between the cytosol and the sarcoplasmic reticulum. The importance of Ca entry from extracellular spaces to the cytosol has gained significant attention over the past decade. Store-operated Ca entry with a low amplitude and relatively slow kinetics is a main extracellular Ca entryway into skeletal muscle. Herein, recent studies on extracellular Ca entry into skeletal muscle are reviewed along with descriptions of the proteins that are related to extracellular Ca entry and their influences on skeletal muscle function and disease.