title: HIV and SIV gp120 binding does not predict coreceptor function.
abstract: Interaction of HIV and SIV Envelope (Env) proteins with viral coreceptors is a critical step in viral entry. By using a sensitive and specific gp120 binding assay, we have identified a discordance between the ability of a coreceptor to support Env-mediated membrane fusion and high-affinity binding of gp120. Direct binding of gp120 from the dual-tropic HIV-1 strain 89.6 was not detectable for any coreceptor that it uses for fusion, while detectable binding of gp120s from the R5 HIV-1 strains JRFL and CM235 and the SIV strain 239 was not measurable for many CCR5 chimeras and mutants that function efficiently as viral coreceptors. In comparison, binding of chemokines to these same mutants was highly predictive of their ability to signal. Thus, gp120 is more sensitive than chemokines to perturbations of CCR5 structure. We conclude that while chemokine binding to CCR5 is a good predictor of chemokine receptor function, gp120 binding does not always predict coreceptor function.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Baik
authors.forename: R W
authors.initials: RW
authors.lastname: Doms
authors.forename: B J
authors.initials: BJ
authors.lastname: Doranz
mesh_terms: D015704:CD4 Antigens / Q000378:metabolism; D002460:Cell Line; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D015658:HIV Infections / Q000821:virology; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D008561:Membrane Fusion; D008562:Membrane Glycoproteins; D019713:Receptors, CCR5 / Q000737:chemistry / Q000378:metabolism*; D019707:Receptors, Chemokine / Q000378:metabolism; D015728:Receptors, HIV / Q000378:metabolism*; D015398:Signal Transduction; D015302:Simian Immunodeficiency Virus / Q000378:metabolism*; D014759:Viral Envelope Proteins
chemical_list: D015704:CD4 Antigens; D015699:HIV Envelope Protein gp120; D008562:Membrane Glycoproteins; D019713:Receptors, CCR5; D019707:Receptors, Chemokine; D015728:Receptors, HIV; D014759:Viral Envelope Proteins; C069623:gp120 protein, Simian immunodeficiency virus