title: Oligomeric structure of the human immunodeficiency virus type 1 envelope protein on the virion surface.
abstract: The envelope protein (Env) of human immunodeficiency virus type 1 forms homo-oligomers in the endoplasmic reticulum. The oligomeric structure of Env is maintained after cleavage in a Golgi compartment and transport to the surfaces of infected cells, where incorporation into budding virions takes place. Here, we use biophysical techniques to assess the oligomeric valency of virion-associated Env prior to fusion activation. Virion-associated Env oligomers were stabilized by chemical cross-linking prior to detergent extraction and were purified by immunoaffinity chromatography. Gel filtration revealed a single predominant oligomeric species, and sedimentation equilibrium analysis-derived mass values indicated a trimeric structure. Determination of the masses of individual Env molecules by scanning transmission electron microscopy demonstrated that virion-associated Env was trimeric, and a triangular morphology was observed in 20 to 30% of the molecules. These results, which firmly establish the oligomeric structure of human immunodeficiency virus virion-associated Env, parallel those of our previous analysis of the simian immunodeficiency virus Env.
authors.affiliation: Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Rob J
authors.initials: RJ
authors.lastname: Center
authors.forename: Richard D
authors.initials: RD
authors.lastname: Leapman
authors.forename: Jacob
authors.initials: J
authors.lastname: Lebowitz
authors.forename: Larry O
authors.initials: LO
authors.lastname: Arthur
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Earl
authors.forename: Bernard
authors.initials: B
authors.lastname: Moss
mesh_terms: D001704:Biopolymers; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D019281:Dimerization; D015497:HIV-1 / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D017348:Microscopy, Electron, Scanning Transmission; D011487:Protein Conformation; D014759:Viral Envelope Proteins / Q000737:chemistry*; D014771:Virion / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D001704:Biopolymers; D014759:Viral Envelope Proteins