CLONING AND CHARACTERIZATION OF MVP17 - A DEVELOPMENTALLY-REGULATED MYELIN PROTEIN IN OLIGODENDROCYTES

The remarkable quantities of myelin membrane produced by oligodendrocy tes has led us to examine the mechanisms involved in the sorting and t ransport of proteins and lipids during myelinogenesis. Noting that it has been proposed that proteins destined for the apical surface of pol arized epithelial cells co-cluster with glycolipid-rich microdomains d uring sorting and transport from the trans-Golgi network (Simons and v an Meer: Biochemistry 27:6197-6202, 1988; Simons and Wandinger-Ness: C ell 62:207-210, 1990), we hypothesized that the glycolipid-rich oligod endrocytes may adopt this mechanism for myelinogenesis. Protein-lipid complexes from oligodendrocytes and myelin were isolated utilizing det ergent insolubility and two-dimensional gel electrophoresis, A develop mentally regulated protein, MVP17 (myelin vesicular protein of 17 kDa) , was identified, Microsequencing of the N-terminal peptide revealed a high homology to human T-cell MAL protein (Alonso and Weissman: Proc Natl Acad Sci USA 84:1997-2001, 1987), The corresponding MVP17 cDNA wa s isolated from an oligodendrocyte cDNA library. The predicted protein sequence showed 88.9% identity with MAL, and the hydrophobicity profi le suggested four transmembrane domains, In vitro translation demonstr ated a signal at the deduced Mr of similar to 17 kDa. Northern analyse s indicated that MVP17 mRNA expression is restricted to brain and kidn ey and that this expression is up-regulated in oligodendrocytes and br ain during the period of active myelination, These data suggest that M VP17 is involved in myelin biogenesis and/or myelin function. (C) 1995 Wiley-Liss, Inc.