Shark CNS myelin contains four polypeptides related to the PNS protein Po of higher classes

The relationship between the proteins of shark central nervous system (CNS) myelin and those of myelin from higher classes has been investigated using antibodies raised against a 31,500 molecular weight polypeptide from shark myelin. The antibodies cross-reacted with 3 shark CNS polypeptides apart from the original antigen, with 2 major polypeptides from shark peripheral nervous system myelin, with the Po protein from chicken and sheep peripheral nervous system myelin, but with none of the components of bovine CNS myelin. It appears that the oligodendroglial cells of the shark synthesize a protein closely related to the Po protein produced by Schwann cells of vertebrate classes above and including chondrichthytes.