Tetraspan proteins

CD9 is a well-characterized hematopoietic tetraspan protein that has been shown to be present in CNS and PNS myelin, although it is present at higher levels in PNS myelin. In other cells, it is involved in integrin signaling and cell adhesion and motility. It is expressed at late stages of myelination and in the CNS is primarily found in paranodal junctions [34]. While compact CNS myelin is apparently normal in CD9-null animals, the paranodal loops are often disconnected from axonal membranes, and the transverse bands of the paranodal loops are lost. In the PNS, in addition to altered paranodes, hypermy-elination occurs. Thus, this tetraspan protein appears to act primarily at paranodes, where it is crucial for normal paranodal junctions. 

Paranodal proteins other than tetraspan proteins. The... 

Bronstein, J. M. Function of tetraspan proteins in the myelin sheath. Curr. Opin. Neurobiol. 10, 552-557, 2000. 

MAL myelin and lymphocyte tetraspan protein NF (i) neurofilament (ii) neurofibromatosis... 

Escola, J.M., Kleijmeer, M.J., Stoorvogel, W., Griffith, J.M., Yoshie, 0. and Geuze, H.J. (1998) Selective enrichment of tetraspan proteins on the internal vesicles of multivesicular endosomes and on exosomes secreted by human B-lymphocytes. J. Biol. Chem. 273, 20121-20127. 

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