title: Characterization of V3 loop-binding protein(s) of Molt-4 and U937 cells.
abstract: The V3 loop in gp120 of human immunodeficiency virus type 1 (HIV-1) is known as a principal neutralizing and cell-tropic determinant. Biotinylated synthetic V3 loop peptides derived from three different HIV-1 strains were used as ligands to identify the cell surface counterreceptor, which may participate in the infection of HIV-1. Two different cell lines, Molt-4 and U937, and three V3 loop peptides derived from LAVELI, HTLV-IIIMN, and HTLV-IIIB strains were used. The binding of HTLV-IIIB-derived peptide to the cell surface was confirmed using 125I-labeled surface proteins of both cell lines. The relative molecular mass of the major radioactive band on the autoradiogram was 32-33 kDa in both cell lines. A protein was purified from the plasma membrane fraction of Molt-4 cells using affinity columns coupled with three different V3 loop peptides. Two major polypeptides (32 and 33 kDa) were eluted from the affinity column. Size-exclusion chromatography showed that the protein migrated as a single peak with a molecular mass of 130 kDa. These proteins were separated by reversed-phase chromatography, which indicated that the 32-kDa protein is more hydrophobic than the 33-kDa protein in Molt-4 cells. A similar but not identical 130-kDa protein with 32- and 33-kDa polypeptides were also purified from U937 cells. These findings indicate that HIV-1 utilizes a tetrameric protein on the surface of Molt-4 and U937 cells on infection.
authors.affiliation: Laboratory for AIDS Immunology, Kyoto University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Xu
authors.forename: T
authors.initials: T
authors.lastname: Murakami
authors.forename: S
authors.initials: S
authors.lastname: Kawase
authors.forename: T
authors.initials: T
authors.lastname: Uchiyama
authors.forename: T
authors.initials: T
authors.lastname: Hattori
mesh_terms: D000595:Amino Acid Sequence; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism / Q000821:virology; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism*; D011485:Protein Binding; D015728:Receptors, HIV / Q000302:isolation & purification / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments; D015728:Receptors, HIV