Muscle, Skeletal, Receptor Tyrosine Kinase (MUSK)

MuSK (for Muscle Specific Kinase) is a receptor tyrosine kinase required for the formation of the neuromuscular junction. It is activated by a nerve-derived proteoglycan called agrin. This protein binds to several receptors on the surface of skeletal muscle. The receptor which seems to be required for formation of the neuromuscular junction (NMJ), which comprises the nerve-muscle synapse is called MuSK (Muscle specific kinase). MuSK is a receptor tyrosine kinase - meaning that it induces cellular signaling by causing the addition of phosphate molecules to particular tyrosines on itself, and on proteins which bind the cytoplasmic domain of the receptor.In mice which are deficient for either agrin or MuSK, the neuromuscular junction does not form. Many other proteins also comprise the NMJ, and are required to maintain its integrity.