The synthesis and acylation of proteolipid proteins where investigated in tissue slices prepared from 19-day-old quaking and normal littermate mouse brain. The mutant CNS had a normal rate of total protein synthesis but synthesis of the myelin-specific proteins, proteolipid protein (PLP) and intermediate protein (IP), was impaired to approximately 50% of control. The acylation of myelin proteins with labeled palmitate was reduced to only about 20% of control. The acylation of two nonmyelin proteolipid proteins was also significantly reduced. The incorporation of palmitate into phospholipids was identical in control and mutant. The results indicate impaired synthesis of PLP and IP and a general deficit in protein acylation in quaking brain.