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. Author manuscript; available in PMC: 2012 Dec 24.
Published in final edited form as: Biol Chem. 2010 Nov;391(11):1341–1363. doi: 10.1515/BC.2010.129

Figure 7. LRP4 serves as a receptor for agrin and as a coreceptor for the tyrosine kinase MUSK in muscle.

Figure 7

(Kim et al. 2008; Zhang et al. 2008). The membrane tyrosine kinase, MUSK, is required for the induction of acetylcholine receptor (AChR) clustering during the formation of neuromuscular junctions (endplates). MUSK does not bind the signaling protein agrin directly, but must form a complex with LRP4, a coreceptor for agrin. Agrin binding to LRP4 enhances complex formation of MUSK with LRP4 and induces transphosphorylation of MUSK followed by acetylcholine receptor (AChR) clustering.