※ Musk family introduction

    MUSK (Muscle Specific Kinase) belongs to receptor tyrosine kinase. One member has been identified in human genome and can be mapped on chromosome 9. The extracellular region of MUSK consists of four immunoglobulin-like domains and a cysteine-rich domain. The intracellular region contains a juxtamembrane domain (JM), which adjacent the transmembrane domain (TM), and a tyrosine kinase domain. Muscle is essential in regulation the formation of NMJ during embryonic development. Studies show that lack of MUSK will lead to NMJs formation defect. MUSK can also mediate AChRs, acetylcholinesterase and postsynaptic proteins targeting to the developing synapse. In addition, MUSK can also contribute to guide the growing motor axons. Furthermore, MUSK can mediate the membrane domain construction through the positive feedback cycle. Studies show that MUSK is associated with some congenital and autoimmune diseases, including muscle weakness, congenital myasthenic syndromes and autoimmune myasthenia gravis (1).

Reference
1. Ghazanfari, N., Fernandez, K.J., Murata, Y., Morsch, M., Ngo, S.T., Reddel, S.W., Noakes, P.G. and Phillips, W.D. (2011) Muscle specific kinase: organiser of synaptic membrane domains. Int J Biochem Cell Biol, 43, 295-298. PMID: 20974278