A tripartite nuclear localization signal in the PDZ-domain protein L-periaxin.

The murine Periaxin gene encodes two PDZ-domain proteins in myelin-forming Schwann cells of the vertebrate peripheral nervous system (Dytrych, L., Sherman, D. L., Gillespie, C. S., and Brophy, P. J. (1998) J. Biol. Chem. 273, 5794-5800). Here we show that L-periaxin is targeted to the nucleus of embryonic Schwann cells. Subsequently, the protein redistributes to the plasma membrane processes of the myelinating Schwann cell where it is believed to function in a signaling complex. In contrast, L-periaxin remains in the nucleus when expressed ectopically in oligodendrocytes, the myelin-forming glia of the central nervous system. The nuclear localization signal (NLS) is basic and tripartite and comprises three signals that act synergistically. Nuclear targeting of L-periaxin is energy-dependent and is inhibited by cell-cell contact. These data show that L-periaxin is a member of a growing family of proteins that can shuttle between the nucleus and cortical signaling/adherence complexes.