(Section 1, Chapter 9, Part 3) Neuroscience Online: An Electronic Textbook for the Neurosciences | Department of Neurobiology and Anatomy - The University of Texas Medical School at Houston

CADHERINS: Encoded by multiple genes; 10 have been characterized in vertebrates. The major N-cadherin in brain is present on most neurons. Adhesion between individual cadherins is by homophilic binding and is Ca²⁺-dependent. N-Cadherin is expressed very early in development & appears to play an important adhesive role throughout the life of an organism. Most neurons express both N-CAMs & N-cadherin.

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.

INTEGRINS: Integrins are involved in adhesion between cell-surfaces and components of the ECM; the adhesive interactions between integrins and other macromolecules is by heterophilic binding. The integrins are transmembrane glycoproteins. The expression of different combinations of integrins on different cells determine which ECM molecules they bind.