Characterization of the shark myelin Po protein.
Myelin, the insulating sheath made by extensive plasma membrane wrapping, is dependent on the presence of highly adhesive molecules that keep the two sides of the membrane in tight contact. The Po glycoprotein (Po) is the major component of the peripheral nervous system (PNS) myelin of mammals. The exact role that Po protein has played in the evolution of myelin is still unclear, but several phylogenetic observations suggest that it is a crucial component in the development of myelin as a multi-lamellar membrane structure. Sharks, which appeared in the fossil record about 400 million years ago, are the first fully myelinated organisms. In this study we investigated the expression pattern of shark myelin Po to suggest a way it might have played a role in the evolution of myelin in the central nervous system. We found that sharks have more than two isoforms (32, 28 and 25 kD), and that some of these might not be fully functional because they lack the domains known for Po homophilic adhesion.
Rotenstein
L
L
California State University Northridge, Biology Department, Northridge, Calif, USA.
Herath
K
K
Gould
R M
RM
de Bellard
M E
ME
D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D015153:Blotting, Western; D002490:Central Nervous System / Q000737:chemistry / Q000196:embryology; D000939:Epitopes / Q000276:immunology; D019143:Evolution, Molecular; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D018993:Myelin P0 Protein / Q000032:analysis / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification; D017933:Peripheral Nervous System / Q000737:chemistry / Q000196:embryology; D020033:Protein Isoforms / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011817:Rabbits; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012754:Sharks / Q000196:embryology / Q000276:immunology / Q000378:metabolism*; D013045:Species Specificity; D048251:Squalus acanthias / Q000276:immunology / Q000378:metabolism*; D014714:Vertebrates / Q000378:metabolism
D000939:Epitopes; D018993:Myelin P0 Protein; D020033:Protein Isoforms