Myelin sheaths: glycoproteins involved in their formation, maintenance and degeneration.
Myelin sheaths are formed around axons by extending, biochemically modifying and spiraling plasma membranes of Schwann cells in the peripheral nervous system (PNS) and oligodendrocytes in the central nervous system (CNS). Because glycoproteins are prominent components of plasma membranes, it is not surprising that they have important roles in the formation, maintenance and degeneration of myelin sheaths. The emphasis in this review is on four integral membrane glycoproteins. Two of them, protein zero (P0) and peripheral myelin protein-22 (PMP-22), are components of compact PNS myelin. The other two are preferentially localized in membranes of sheaths that are distinct from compact myelin. One is the myelin-associated glycoprotein, which is localized at the inside of sheaths where it functions in glia-axon interactions in both the PNS and CNS. The other is the myelin-oligodendrocyte glycoprotein, which is preferentially localized on the outside of CNS myelin sheaths and appears to be an important target antigen in autoimmune demyelinating diseases such as multiple sclerosis.
Quarles
R H
RH
Myelin and Brain Development Section, Laboratory of Molecular and Cellular Neurobiology, National Institute of Neurological Disorders and Stroke, Room 2 A28, Building 49, MSC 4440, 49 Convent Drive, NIH, Bethesda Maryland 20892, USA. quarlesr@ninds.nih.gov
D000818:Animals; D002144:Callithrix; D002462:Cell Membrane / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D051379:Mice; D018993:Myelin P0 Protein / Q000378:metabolism; D009185:Myelin Proteins / Q000378:metabolism; D009186:Myelin Sheath / Q000378:metabolism* / Q000473:pathology; D018992:Myelin-Associated Glycoprotein / Q000378:metabolism; D063308:Myelin-Oligodendrocyte Glycoprotein; D009410:Nerve Degeneration / Q000378:metabolism
D006023:Glycoproteins; C571327:Mog protein, mouse; D018993:Myelin P0 Protein; D009185:Myelin Proteins; D018992:Myelin-Associated Glycoprotein; D063308:Myelin-Oligodendrocyte Glycoprotein; C489545:Pmp22 protein, mouse