Figure 1.

Structural domains of rapsyn. The N-terminal myristoylation site (Myr) targets rapsyn to the plasma membrane. The first two TPR domains are sufficient to mediate rapsyn self-clustering. Whether other TPR domains also can serve this function remains to be determined. The ability of rapsyn to promote AChR clustering appears to depend on a putative coiled-coil motif. TPR domains not involved in rapsyn self-association as well as the zinc ring finger (RING) domain are likely to be sites of interaction with other postsynaptic proteins. The function of the phosphorylation site (P) is unknown.