Myelin-associated glycoprotein interacts with neurons via a sialic acid binding site at ARG118 and distinct neurite inhibition site

The role of sialic acid-binding epitope of myelin-associated glycoprotein (MAG) on neurite outgrowth was demonstrated through site-directed mutagenesis. Results show that the neurite inhibitory activity of MAG is distinct from its sialic acid site since by itself, sialic acid binding is not sufficient to effect inhibition of axonal growth. MAG's sialic acid-dependent binding is lost when it is mutated to either aspartic acid or alanine. Meanwhile MAG retains its ability to inhibit axonal regeneration when it is expressed at the surface of either Schwann or Chinese hamster ovary cells.