SELF-ASSOCIATION OF TRUNCATED FORMS OF HIV-1 GP120

HIV-1 gp120 and truncated forms were expressed in HeLa T4 cells by vac cinia recombinant viruses. The truncated gp120 molecules consisted of N-terminal overlapping envelope proteins of 204, 287 and 393 amino aci ds respectively. Immunoprecipitation with specific monoclonal antibodi es and SDS-PAGE analyses of HIV-1 gp120 revealed bands corresponding t sigma low amounts of secreted and cell-bound stable dimers. In contra st, the truncated forms of gp120 expressed larger amounts of SDS-stabl e putative dimers and the amounts observed were inversely proportional to their size. The shortest gp120 mutant (204 aa) was found to be sec reted almost exclusively as a dimer. The processing of gp120 and its t runcated forms was further investigated in the presence of inhibitors of N-glycosylation. Monomers and dimers migrated on gels with the same relative changes, confirming that the protein with the higher molecul ar weight is a multimer of the smaller one. The putative dimeric form of the truncated gp120s could be stabilized by chemical cross-linking. Finally, the possible existence of an association domain in the N-ter minal 204 amino acids (aa)of gp120 is discussed. (C) 1997 Elsevier Sci ence B.V.