DIFFERENTIAL GLYCOSYLATION OF TRACTIN AND LEECHCAM, 2 NOVEL IG SUPERFAMILY MEMBERS, REGULATES NEURITE EXTENSION AND FASCICLE FORMATION

By immunoaffinity purification with the mAb Lan3-2, we have identified two novel Ig superfamily members, Tractin and LeechCAM. LeechCAM is a n NCAM/FasII/ApCAM homologue, whereas Tractin is a cleaved protein wit h several unique features that include a PG/YG repeat domain that may be part of or interact with the extracellular matrix. Tractin and Leec hCAM are widely expressed neural proteins that are differentially glyc osylated in sets and subsets of peripheral sensory neurons that form s pecific fascicles in the central nervous system. In vivo antibody pert urbation of the Lan3-2 glycoepitope demonstrates that it can selective ly regulate extension of neurites and filopodia. Thus, these experimen ts provide evidence that differential glycosylation can confer functio nal diversity and specificity to widely expressed neural proteins.