A focus on extracellular Ca2+ entry into skeletal muscle

The main task of skeletal muscle is contraction and relaxation for body movement and posture maintenance. During contraction and relaxation, Ca2+ in the cytosol has a critical role in activating and deactivating a series of contractile proteins. In skeletal muscle, the cytosolic Ca2+ level is mainly determined by Ca2+ movements between the cytosol and the sarcoplasmic reticulum. The importance of Ca2+ entry from extracellular spaces to the cytosol has gained significant attention over the past decade. Store-operated Ca2+ entry with a low amplitude and relatively slow kinetics is a main extracellular Ca2+ entryway into skeletal muscle. Herein, recent studies on extracellular Ca2+ entry into skeletal muscle are reviewed along with descriptions of the proteins that are related to extracellular Ca2+ entry and their influences on skeletal muscle function and disease.