Abstract
Human immunodeficiency virus (HIV) and simian immunodeficiency virus Nef proteins contain a conserved motif with the minimal consensus (PxxP) site for Src homology region 3 (SH3)-mediated protein-protein interactions. Nef PxxP motifs show specific binding to biotinylated SH3 domains of Hck and Lyn, but not to those of other tested Src family kinases or less related proteins. A unique cooperative role of a distant proline is also observed. Endogenous Hck of monocytic U937 cells can be specifically precipitated by matrix-bound HIV-1 Nef, but not by mutant protein lacking PxxP. Intact Nef PxxP motifs are dispensable for Nef-induced CD4 down-regulation, but are required for the higher in vitro replicative potential of Nef+ viruses. Thus, CD4 down-regulation and promotion of viral growth are two distinct functions of Nef, and the latter is mediated via SH3 binding.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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CD4 Antigens / genetics
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Down-Regulation
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Gene Products, nef / genetics
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Gene Products, nef / metabolism*
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Glutathione Transferase / biosynthesis
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Glutathione Transferase / genetics
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HIV-1 / genetics
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HIV-1 / growth & development*
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HIV-1 / immunology
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Humans
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Leukocytes, Mononuclear / immunology
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Leukocytes, Mononuclear / virology
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Proline / metabolism
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Protein Binding
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Protein-Tyrosine Kinases / classification
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Protein-Tyrosine Kinases / metabolism*
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins c-hck
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Recombinant Fusion Proteins / metabolism
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Structure-Activity Relationship
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nef Gene Products, Human Immunodeficiency Virus
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src-Family Kinases*
Substances
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CD4 Antigens
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Gene Products, nef
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Proto-Oncogene Proteins
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Recombinant Fusion Proteins
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nef Gene Products, Human Immunodeficiency Virus
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Proline
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Glutathione Transferase
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Protein-Tyrosine Kinases
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HCK protein, human
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Proto-Oncogene Proteins c-hck
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lyn protein-tyrosine kinase
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src-Family Kinases