L-Periaxin (L-PRX) is a membrane protein that is expressed in Schwann cells of the peripheral nervous system where it acts as a key component of the dystrophin glycoprotein complex (DGC). PRX is required for the proper localization of a dystrophin-related protein DRP2 to sites of apposition between the Schwann cell plasma membrane and the abaxonal surface of the myelin sheath (Sherman et al, 2001; Sherman et al, 2012; Court et al, 2004; Court et al, 2009; reviewed in Masaki and Matsumura, 2010). The spectrin repeats of DRP2 and the basic subdomains of L-PRZ mediate direct interaction between the two proteins. S-PRZ, an alternate isofom that lacks the basic subdomains of L-PRZ, does not interact with DRP2 (Sherman et al, 2001). The complex of L-PRX and DRP2 also interact with other dystrophin-related proteins such as utrophin, as well as dystroglycan and components of the basal lumina, such as laminin-211 (Yamada et al, 1994; Yamada et al, 1996; Sherman et al, 2001).
PRZ and DRP2 have partially overlapping but distinct roles in myelin sheath formation. Both are required for the formation of appositions between the plasma membrane and the myelin sheath and for the formation of Cajal bodies. PRX also contributes to normal Schwann cell elongation and regulation of internode space along the axon, which is required for nerve conduction, while DRP2 is dispensable for these activities (Court et al, 2009; Sherman et al, 2012;)