DEVELOPMENTAL CHANGES OF MYELIN PROTEINS IN THE CHICK PERIPHERAL NERVE

Abstract— Developmental changes of myelin proteins in chick sciatic nerve were studied at the stage of myelination by sodium dodecylsulfate (SDS)‐polyacrylamide gel electrophoresis. The myelin of adult hen peripheral nervous system (PNS) contained two glycoproteins (BR‐P0 and PASII), both of which are unique to PNS myelin, in addition to the basic encephalitogenic protein, BP, which is common to CNS and PNS myelin. The other basic protein (BF‐P2) found in the PNS of other species was not definitely detectable in hen PNS. At the early stages of myelination (from 14 to 18 embryonic days) the amounts of myelin proteins increased rapidly in parallel with the increase in number of layers of the myelin sheath of the PNS. At 14 embryonic days high molecular weight proteins were dominant, while myelin specific proteins were barely detectable in the PNS myelin fraction. At 18 embryonic days, however, BR‐PO, BP and PASII proteins became the main protein components of the PNS myelin, whereas high molecular weight proteins decreased in quantitative importance during development. At the early stage of myelination other glycoproteins were also detectable in the PNS myelin. Radioactive fucose was actively incorporated into the two glycoproteins, BR‐P0 and PASII, at the early stage of myelination in vivo. These results suggested that myelin proteins especially glycoproteins, may play an important role in PNS myelin formation.