Myelin P0-protein, more than just a structural protein?

The protein P0 has long been proposed to be responsible for the compact nature of peripheral myelin through interactions of both its extracellular and cytoplasmic domains. Recent studies support such a role for P0's extracellular region while more precise mapping of its adhesive domains are ongoing. As P0 is a member of the immunoglobulin gene superfamily and perhaps bears the closest similarity to the ancestral molecule of this whole family, these studies may also have more general implications for adhesive interactions. In addition, although long believed to be purely an inert, structural molecule, P0 has been reported to promote neurite outgrowth, which suggests a more dynamic role for this interesting molecule.