Topography of N-CAM structural and functional determinants. I. Classification of monoclonal antibody epitopes.

TLDR

The study classifies monoclonal antibody epitopes to map key structural and functional features of N‑CAM, providing probes for its analysis. By testing antibody interference, the authors mapped functional epitopes to be spatially close relative to other determinants on N‑CAM. Twelve distinct N‑CAM epitopes were mapped: seven amino‑terminal antibodies modulate adhesion (four inhibit, three enhance), three central epitopes depend on polypeptide or carbohydrate, and two intracellular antibodies target the largest polypeptide form.

Abstract

12 distinct neural cell adhesion molecule (N-CAM) epitopes, each recognized by a different monoclonal antibody (mAb), have been characterized in terms of the major structural and functional features of the molecule. Seven antibodies, each recognizing the amino-terminal region of the molecule, altered the rate of N-CAM-mediated adhesion. Four of these were inhibitors, two of which also recognized a heparin-binding N-CAM fragment. The other three antibodies specifically enhanced the rate of N-CAM-mediated adhesion. Three epitopes, one polypeptide- and two carbohydrate-dependent, were associated with the sialic acid-rich central portion of the molecule. The remaining two antibodies were found to react with intracellular determinants, and are specific for the largest of the three major N-CAM polypeptide forms. Studies on the ability of one antibody to hinder recognition of native N-CAM by another antibody suggested that the epitopes associated with N-CAM binding functions are in close proximity compared with the other determinants. The classification of these mAb epitopes has allowed the topographical placement of key N-CAM features, as described in the following paper, and provides valuable probes for analysis of both the structure and function of N-CAM.