N-CAMs (neuronal cell adhesion molecule): N-CAMs were first discovered
because of their roles in the development of retina neurons. They are
encoded by one gene; 3 major forms are produced by mRNA splicing. Each
N-CAM is extensively modified by posttranslational glycosylation; in
the developing embryo the N-CAMs have a very high sialic acid content
(30% by weight) which results in a lower affinity between N-CAMs (they
are only 10% by weight sialic acid in the adult). Each N-CAM binds to
another N-CAM, which is called homophilic binding. Also shown is an
example of cell-cell adhesion mediated by heterophilic binding between
TAG-1 and Axonin, two different cell adhesion molecules.