Rapsyn
43 kDa receptor-associated protein of the synapse (rapsyn) is a protein that in humans is encoded by the RAPSN gene.
This protein belongs to a family of proteins that are receptor associated proteins of the synapse. It contains a conserved cAMP-dependent protein kinase phosphorylation site. It is believed to play some role in anchoring or stabilizing the nicotinic acetylcholine receptor at synaptic sites. It may link the receptor to the underlying postsynaptic cytoskeleton, possibly by direct association with actin or spectrin. Two splice variants have been identified for this gene.
In the neuromuscular junction there is a vital pathway that maintains synaptic structure and results in the aggregation and localization of the acetylcholine receptor (AChR) on the postsynaptic folds. This pathway consists of agrin, muscle-specific tyrosine kinase (MuSK protein), AChRs and the AChR-clustering protein rapsyn, encoded by RAPSN. Genetic mutations of the proteins in the neuromuscular junction are associated with Congenital myasthenic syndrome (CMS). Postsynaptic defects are the most frequent cause of CMS and often result in abnormalities in the acetylcholine receptor. The vast majority of mutations causing CMS are found in the AChR subunits and rapsyn genes.
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