MuSK protein
- OMIM: 601 296
- UniProt: O15146
The muscle-specific receptor tyrosine kinase ( MuSK ), and muscle -specific kinase, is a "single -pass" transmembrane protein that is formed in muscle cells in the postsynaptic membrane of the neuromuscular junction. It is made of MuSK gene, which is localized in humans on chromosome 9, encoding ( locus 9q31 ). The enzyme is involved as to the tyrosine phosphorylation of tyrosine residues. It plays an important role both in the formation ( embryonic ) as well as in the maintenance of the neuromuscular junction.
Protein structure
MuSK has in the N- terminal region, which is located extracellularly, 3 immunoglobulin-like (Ig -like) domains, and a cysteine-rich frizzled -like domain. C -terminally located tyrosine kinase domain.
Function
The muscle-specific receptor tyrosine kinase is activated by the enzyme agrin that is secreted by motor neurons, that is, from nerve terminals at the neuromuscular junction. Activation via a signal transduction for rapsyn - dependent " clusters " of acetylcholine receptors.
Medical importance of MuSK
Certain mutations in MUSK gene lead to congenital myasthenic syndrome with acetylcholine receptor deficiency ( congenital myasthenic syndrome engl. with acetylcholine receptor deficiency, or CMS for short - ACHRD ). Antibodies against the MuSK protein may lead to an autoimmune disease, myasthenia gravis.