This research on myelinogenesis explores the hypothesis that the intracellular processing and assembly of myelin is defective in the quaking mutant. This thesis has been developed by determining the short-term rates of biosynthesis of the major proteins and lipids in the CNS of quaking mutant and the rates of their incorporation into myelin and other subcellular membranes. We shall proceed with further detailed studies of this mutant examining the steps of intracellular protein passage in the process of assemply of the myelin membrane. The main thrust will be to examine the distribution and intracellular processing of myelin protein of two types: intrinsic (the proteolipid protein [PLP] and myelin-associated glycoprotein [MAG]) and peripheral (the four low molecular weight myelin basic proteins [MBPs]). The intracellular processing of myelin proteins subject to post-translational modification in oligodendroglial endomembranes will be examined in quaking CNS (and their analogues in the Schwann cell in PNS) with reference to oligosaccharide processing and acylation.