Isolation and analysis of the gene encoding peripheral myelin protein zero

Abstract

We have isolated the gene encoding the Schwann cell glycoprotein P 0, the major structural protein of the peripheral myelin sheath. In rats and mice, this gene is split into six exons distributed over 7 kb of DNA. The segregation of these exons is consistent with the functional segregation of the P 0 protein into extracellular, membrane-spanning, and cytoplasmic domains. We find that the P 0 extracellular domain is similar in structure to a single immunoglobulin variable region domain. In contrast to prototypical immunoglobulin domains, however, this P 0 domain is encoded by two exons, the partitioning of which provides genetic evidence for the evolution of immunoglobulin-related domains from an ancestral half-domain. We also describe procedures for transfection of cultures of nontransformed rat Schwann cells and use these procedures to show that the Schwann cell-specific expression of the P 0 gene is controlled by cis-acting elements localized upstream of exon 1.