title: Human immunodeficiency virus type 1 Vpu protein is an oligomeric type I integral membrane protein.
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.
authors.affiliation: Laboratory of Molecular Microbiology, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: F
authors.initials: F
authors.lastname: Maldarelli
authors.forename: M Y
authors.initials: MY
authors.lastname: Chen
authors.forename: R L
authors.initials: RL
authors.lastname: Willey
authors.forename: K
authors.initials: K
authors.lastname: Strebel
mesh_terms: D000818:Animals; D001483:Base Sequence; D015704:CD4 Antigens / Q000235:genetics / Q000378:metabolism; D004285:Dogs; D015696:Gene Products, tat / Q000302:isolation & purification / Q000378:metabolism; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism*; D054298:Human Immunodeficiency Virus Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D014176:Protein Biosynthesis; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping; D012156:Reticulocytes / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism; D014158:Transcription, Genetic; D054334:Viral Regulatory and Accessory Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D054322:tat Gene Products, Human Immunodeficiency Virus; D000086082:Viroporin Proteins
chemical_list: D015704:CD4 Antigens; D015696:Gene Products, tat; D054298:Human Immunodeficiency Virus Proteins; D008565:Membrane Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D054334:Viral Regulatory and Accessory Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins