43 kDa receptor-associated protein of the synapse, also known as RAPSN, is expressed in the postsynaptic membrane of skeletal muscle. RAPSN is required for the clustering of nicotinic acetylcholine receptors (nAChR). It self-associates through at least two of its seven tetra-tricopeptide repeats (TPRs). RAPSN interacts with the large intracellular domain of the nAChR a subunit through the hydrophobic surface of the coiled-coil domain. This protein modifies trafficking of AChR within the cell. Overexpression inhibits agrin-induced AChR clustering pathway. Recombinant human RAPSN protein, fused to His-tag at N-terminus, was expressed in E.coli.