UNIQUE GLYCOPROTEIN-PROTEOGLYCAN COMPLEX DEFINED BY MONOCLONAL-ANTIBODY ON HUMAN-MELANOMA CELLS

A monoclonal antibody, 9.2.27, with a high specificity for human melanoma cell surfaces was utilized for biosynthetic studies in M21 human melanoma cells to define a unique antigenic complex consisting of a 250-kilodalton N-linked glycoprotein and a high MW proteoglycan component larger than 400 kilodaltons. The 250-kilodalton glycoprotein has endoglycosidase H-sensitive precursors and shows a lower apparent MW after treatment with neuraminidase. The biosynthesis of the proteoglycan component is inhibited by exposure of M21 cells to the monovalent ionophore monensin; this component can be labeled biosynthetically with 35SO4, is sensitive to .beta.-elimination in dilute base, and is degraded by chondroitinase AC and ABC lyases, suggesting that it is a chondroitin sulfate proteoglycan. The antigenic determinant recognized by monoclonal antibody 9.2.27 is located on a glycoprotein-proteoglycan complex which may have unique implications for the interaction of glyconconjugates at the human melanoma tumor cell surface.