Developmental expression of OAP‐1/Tspan‐3, a member of the tetraspanin superfamily

OSP/claudin‐11‐associated protein (OAP‐1/Tspan‐3), originally isolated by yeast two‐hybrid screening using OSP/claudin‐11 (oligodendrocyte‐specific protein) as bait, is a member of the tetraspanin superfamily and OAP‐1/Tspan‐3, OSP/claudin‐11, and β1 integrin form a protein complex that seems to be involved in oligodendrocyte proliferation and migration. This study investigated the temporal and regional expression, glycosylation status, and tissue distribution of OAP‐1/Tspan‐3. OAP‐1/Tspan‐3 mRNA was expressed as a single transcript throughout brain development, with high levels of expression in the germinal zones. OAP‐1/Tspan‐3 protein contains N‐terminal glycosylation sites in extracellular loop 2 and deglycosylation studies indicated a decrease in apparent molecular weight of OAP‐1/Tspan‐3, consistent with removal of N‐glycans. Similar to OSP/claudin‐11, OAP‐1/Tspan‐3 is expressed in all stages of oligodendrocyte development and in the myelin sheath. Unlike OSP/claudin‐11, however, it is expressed in all cell types tested in the central nervous system (CNS), including neurons and astrocytes. The association of OAP‐1/Tspan‐3 with OSP/claudin‐11 and β1 integrin, its subcellular distribution as a cell surface, membrane‐spanning glycoprotein, and its widespread distribution supports its potential role in cell migration, proliferation, and interactions between cells and extracellular matrix. © 2004 Wiley‐Liss, Inc.