Heavy and light chain sequences of four monoclonal antibodies that bind galactosylgloboside (GalGb4).

We recently described IgM monoclonal antibodies directed against the glycospingolipid galactosylgloboside (GalGb4; Marcus, M. D. et al., Arch. Biochem. Biophys, 1988.262: 620). We now present the nucleotide and deduced amino acid sequences of the heavy and light chains of these antibodies. The antibodies were generated in a single fusion, their heavy as well as their light chains are almost identical, and they appear to be clonally related. The light chains were encoded by J kappa 5 and a V kappa gene belonging to the Ox1 family, but they are only 93% homologous to the most closely related germ-line gene, and they are probably encoded by a germ-line gene that has not yet been identified. The heavy chains were all encoded by VH441 and JH2, and have identical N segments. The VH441 germ-line gene encodes a potential glycosylation site at Asn58 in the complementarity-determining region 2. This site, which has been retained in all VH441-encoded monoclonal antibodies sequenced previously, was mutated out by a single base change in all four anti-GalGb4 antibodies.