Mao, YoudongWang, LipingGu, ChristopherHerschhorn, AlonXiang, Shi-HuaHaim, HillelYang, XinzhenSodroski, Joseph2013-05-212012Mao, Youdong, Liping Wang, Christopher Gu, Alon Herschhorn, Shi-Hua Xiang, Hillel Haim, Xinzhen Yang, and Joseph Sodroski. 2012. Subunit organization of the membrane-bound hiv-1 envelope glycoprotein trimer. Nature structural & molecular biology 19(9): 893-899.1545-9993http://nrs.harvard.edu/urn-3:HUL.InstRepos:10646780The trimeric human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) spike is a molecular machine that mediates virus entry into host cells and is the sole target for virus-neutralizing antibodies. The mature Env spike results from cleavage of a trimeric gp160 precursor into three gp120 and three gp41 subunits. Here we describe an ~11-Å cryo-EM structure of the trimeric HIV-1 Env precursor in its unliganded state. The three gp120 and three gp41 subunits form a cage-like structure with an interior void surrounding the trimer axis. Interprotomer contacts are limited to the gp41 transmembrane region, the torus-like gp41 ectodomain, and a gp120 trimer association domain composed of the V1/V2 and V3 variable regions. The cage-like architecture, which is unique among characterized viral envelope proteins, restricts antibody access, reflecting requirements imposed by HIV-1 persistence in the host.en-USJournal Article2013-05-2110.1038/nsmb.2351