A phosphatidylinositol-linked peanut agglutinin-binding glycoprotein in central nervous system myelin and on oligodendrocytes

Here we report the isolation and initial biochemical characterization of a 120-kD peanut agglutinin-binding glycoprotein from the adult human central nervous system (CNS), which is anchored to membranes through a phosphatidylinositol linkage. Myelin incubated with phosphatidylinositol-specific phospholipase C released the protein as a soluble polypeptide of 105 kD, which was isolated with peanut agglutinin-agarose affinity chromatography. The protein was found to be highly glycosylated. The protein appears to be confined to the CNS, where its developmental expression is region specific and parallels myelination. It is in greater quantity in white matter than in gray matter and it is in isolated human CNS myelin. Furthermore, ovine oligodendrocytes in culture contain the protein on their surfaces and release it into the supernatant as a soluble 105-kD form. We call this protein the oligodendrocyte-myelin protein.