PERIAXIN, A NOVEL PROTEIN OF MYELINATING SCHWANN-CELLS WITH A POSSIBLE ROLE IN AXONAL ENSHEATHMENT

We report the cloning and subcellular localization of a novel Schwann cell-specific protein of 147 kd that we have named periaxin. Periaxin has a remarkable domain of repetitive pentameric units in the primary sequence. It is expressed in the first uncompacted whorls of membrane that ensheathe the axon, and further synthesis of the protein in the r at sciatic nerve parallels the deposition of myelin. In mature myelin, periaxin colocalizes with the myelin-associated glycoprotein in the c ytoplasm-filled periaxonal regions of the sheath but is excluded from compact myelin. We propose that periaxin has a role in axon-glial inte ractions, possibly by interacting with the cytoplasmic domains of inte gral membrane proteins such as myelin-associated glycoprotein in the p eriaxonal regions of the Schwann cell plasma membrane.