Proteolipid proteins: structure and genetic expression in normal and myelin-deficient mutant mice

Myelin, the unique product of a glial cell membrane that electrically insulates the nerve axon, is composed of relatively few major protein components. The recent characterization of these proteins by molecular cloning techniques has raised interest in studies of myelin formation at the molecular level. Proteolipids, a family of integral membrane proteins specific to myelin of the central nervous system, are highly abundant and serve a structural function in the architecture of the multilayered sheath. A critical role for proteolipid protein (PLP) expression during normal development and for the survival of the myelinating oligodendrocyte is reflected in severe developmental disorders of mice that result from genetic mutations in the single structural gene for PLP. The analysis of PLP gene expression in these mutants and other dysmyelinating mouse strains has revealed interactions between myelin-specific genes that may underlie the coordinate development of oligodendrocytes and myelination in the brain.