Proc Natl Acad Sci U S A 1984 Nov 01;8121:6881-5.

Evolutionary conservation of key structures and binding functions of neural cell adhesion molecules.

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The neural cell adhesion molecule N-CAM is a sialic acid-rich, cell surface glycoprotein that mediates cell adhesion by a homophilic mechanism. Its binding function has been implicated in both morphogenesis and histogenesis; during development it changes in amount at the cell surface and perinatally it undergoes a decrease in sialic acid content (embryonic--adult conversion) with an increase in binding efficacy. In the present study, salient aspects of the structure and the mutual binding specificities of N-CAMs from a variety of vertebrate species were examined to determine whether (N-CAM)-mediated adhesion mechanisms have been conserved during evolution. N-CAM immunoreactivity was detected in a series of polypeptides of characteristic molecular weight extracted from brain tissues of all vertebrate species tested, including mammals, birds, reptiles, amphibia, and bony and cartilaginous fish. Adhesion mediated by N-CAM occurred across species lines as indicated by the co-aggregation of chicken and mouse neural cells. By using a quantitative membrane vesicle aggregation assay, the efficacy of cross-species brain membrane vesicle adhesion in various pairings (chicken-mouse, chicken-frog, mouse-frog) was found to be similar to the efficacy of intra-species adhesion. Effective cross-species aggregation of brain membrane vesicles also occurred in embryonic-embryonic, adult-adult, and embryonic-adult pairings. In a control experiment, embryonic chicken liver membrane vesicles (which do not contain N-CAM) did not co-aggregate with embryonic chicken brain membrane vesicles. Cross-species co-aggregation could be inhibited by Fab' fragments of antibodies of N-CAM and was most effectively inhibited in the presence of mixtures made from the Fab' fragments of specific antibodies prepared against the N-CAMs from each of the animal species constituting a co-aggregating pair. These results suggest that, in accord with the proposed role of N-CAM as a regulator of morphogenesis, both the specificity of the binding region of the molecule and its basic chemical structure have been highly conserved during evolution.

???displayArticle.pubmedLink??? 6208560
???displayArticle.pmcLink??? PMC392036
???displayArticle.link??? Proc Natl Acad Sci U S A
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Species referenced: Xenopus laevis
Genes referenced: ncam1

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