Abstract
The human immunodeficiency virus type 1 Vpu protein is a 16-kDa phosphoprotein which enhances the efficiency of virion production and induces rapid degradation of CD4, the cellular receptor for human immunodeficiency virus. The topology of membrane-inserted Vpu was investigated by using in vitro-synthesized Vpu cotranslationally inserted into canine microsomal membranes. Proteolytic digestion and immunoprecipitation studies revealed that Vpu was a type I integral membrane protein, with the hydrophilic domain projecting from the cytoplasmic membrane face. In addition, several high-molecular-weight proteins containing Vpu were identified by chemical cross-linking. Such complexes also formed when wild-type Vpu and a Tat-Vpu fusion protein were coexpressed. Subsequent analysis by one- and two-dimensional electrophoresis revealed that these high-molecular-weight complexes consisted of homo-oligomers of Vpu. These findings indicate that Vpu is a type I integral membrane protein capable of multimerization.
MeSH terms
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Animals
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Base Sequence
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CD4 Antigens / genetics
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CD4 Antigens / metabolism
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Dogs
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Gene Products, tat / isolation & purification
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Gene Products, tat / metabolism
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HIV-1 / genetics
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HIV-1 / metabolism*
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Human Immunodeficiency Virus Proteins
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Membrane Proteins / genetics
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Membrane Proteins / isolation & purification
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Membrane Proteins / metabolism*
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Microsomes / metabolism
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Molecular Sequence Data
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Oligodeoxyribonucleotides
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Protein Biosynthesis
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Rabbits
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Recombinant Fusion Proteins / isolation & purification
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Recombinant Fusion Proteins / metabolism
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Restriction Mapping
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Reticulocytes / metabolism
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T-Lymphocytes / metabolism
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Transcription, Genetic
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Viral Regulatory and Accessory Proteins / genetics
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Viral Regulatory and Accessory Proteins / isolation & purification
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Viral Regulatory and Accessory Proteins / metabolism*
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tat Gene Products, Human Immunodeficiency Virus
Substances
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CD4 Antigens
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Gene Products, tat
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Human Immunodeficiency Virus Proteins
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Membrane Proteins
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Oligodeoxyribonucleotides
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Recombinant Fusion Proteins
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Viral Regulatory and Accessory Proteins
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tat Gene Products, Human Immunodeficiency Virus
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vpu protein, Human immunodeficiency virus 1