<p> Neuromuscular junction formation relies upon the clustering of acetylcholine receptors and other proteins in the muscle membrane. Rapsyn is a peripheral membrane protein that is selectively concentrated at the neuromuscular junction and is essential for the formation of synaptic acetylcholine receptor aggregates. Acetylcholine receptors fail to aggregate beneath nerve terminals in mice where rapsyn has been knocked out. The N-terminal six amino acids of rapsyn are its myristoylation site, and myristoylation is necessary for the targeting of the protein to the membrane [<cite idref="PUB00044454"/>]. </p>