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Oligomeric structure of the human immunodeficiency virus type 1 envelope protein on the virion surface.

Center RJ, Leapman RD, Lebowitz J, Arthur LO, Earl PL, Moss B

  • Journal Journal of virology

  • Published 09 Aug 2002

  • Volume 76

  • ISSUE 15

  • Pagination 7863-7

  • DOI 10.1128/jvi.76.15.7863-7867.2002


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.