MYELIN MEMBRANE BIOGENESIS BY OLIGODENDROCYTES - DEVELOPMENTAL REGULATION OF LOW-MOLECULAR-WEIGHT GTP-BINDING PROTEINS

Oligodendrocytes synthesize dramatic amounts of myelin membrane. We hy pothesized that this requires unique aspects of vesicular trafficking. Specific stages of the oligodendrocyte lineage were assayed for low m olecular weight GTP-binding proteins implicated in the regulation of v esicular transport pathway (two dimensional gel electrophoresis, [alph a-P-32]GTP overlay). Consistent with the hypothesis, as oligodendrocyt es differentiate from early progenitors to mature myelin-producing cel ls, greater than or equal to 12 small GTP-binding proteins become up-r egulated. Myelin membrane also has a complex pattern of GTP-binding pr oteins. Several of these proteins may be specific to oligodendrocytes, suggesting that oligodendrocytes may utilize cell-type specific GTP-b inding proteins for biogenesis and maintenance of the myelin membrane.