♦Envelope glycoprotein gp160 (Env polyprotein) [Cleaved into: Surface protein gp120 (SU) (Glycoprotein 120) (gp120)
♦ Transmembrane protein gp41 (TM) (Glycoprotein 41) (gp41)]

NC_001802.1 ;  AF033819.3 

MRVMEMRKNCQHLWKWGTMLLGMLMICSAAEDLWVTVYYGVPVWKEATTTLFCASEAKAYKTEVHNVWAKHACVPTDPNPQEVLLENVTENFNMWKNNMV
EQMHEDIISLWDQSLKPCVKLTPLCVTLNCTDANLNGTNVTSSSGGTMMENGEIKNCSFQVTTSRRDKTQKKYALFYKLDVVPIEKGNISPKNNTSNNTS
YGNYTLIHCNSSVITQACPKVSFEPIPIHYCTPAGFAILKCNDKKFNGTGPCKNVSTVQCTHGIRPVVSTQLLLNGSLAEEEVVIRSENFTDNVKTIIVQ
LNASVQINCTRPNNNTRKSITKGPGRVIYATGQIIGDIRKAHCNLSRAQWNNTLKQVVTKLREQFDNKTIVFTSSSGGDPEIVLHSFNCGGEFFYCNTTQ
LFNSTWNSTEGSNNTGGNDTITLPCRIKQIVNMWQEVGKAMYAPPISGQIKCISNITGLLLTRDGGEDTTNTTEIFRLGGGNMRDNWRSELYKYKVVRIE
PLGVAPTRAKRRVVQREKRAVGTIGAMFLGFLGAAGSTMGAGSITLTVQARHLLSGIVQQQNNLLRAIEAQQHLLQLTVWGIKQLQARVLAVERYLRDQQ
LLGIWGCSGKLICTTTVPWNASWSNKSLNMIWNNMTWMQWEREIDNYTGIIYNLLEESQNQQEKNEQELLELDKWANLWNWFDITQWLWYIRIFIMIVGG
LVGLKIVFAVLSIVNRVRQGYSPLSFQTHLPAPRGPDRPEGIEGEGGERDRDRSGGAVNGFLTLIWDDLWTLCSFSYHRLRDLLLIVVRIVELLGRRGWE
ALKYWWNLLQYWSQELKNSAVSLLNTTAIAVAEGTDRIIEVAQRILRAFLHIPRRIRQGLERALL

♦Envelope glycoprotein gp160: Oligomerizes in the host endoplasmic reticulum into predominantly trimers. In a second time, gp160 transits in the host Golgi, where glycosylation is completed. The precursor is then proteolytically cleaved in the trans-Golgi and thereby activated by cellular furin or furin-like proteases to produce gp120 and gp41.
♦ Surface protein gp120: Attaches the virus to the host lymphoid cell by binding to the primary receptor CD4. This interaction induces a structural rearrangement creating a high affinity binding site for a chemokine coreceptor like CXCR4 and/or CCR5. Acts as a ligand for CD209/DC-SIGN and CLEC4M/DC-SIGNR, which are respectively found on dendritic cells (DCs), and on endothelial cells of liver sinusoids and lymph node sinuses. These interactions allow capture of viral particles at mucosal surfaces by these cells and subsequent transmission to permissive cells. HIV subverts the migration properties of dendritic cells to gain access to CD4+ T-cells in lymph nodes. Virus transmission to permissive T-cells occurs either in trans (without DCs infection, through viral capture and transmission), or in cis (following DCs productive infection, through the usual CD4-gp120 interaction), thereby inducing a robust infection. In trans infection, bound virions remain infectious over days and it is proposed that they are not degraded, but protected in non-lysosomal acidic organelles within the DCs close to the cell membrane thus contributing to the viral infectious potential during DCs' migration from the periphery to the lymphoid tissues. On arrival at lymphoid tissues, intact virions recycle back to DCs' cell surface allowing virus transmission to CD4+ T-cells.
♦ Transmembrane protein gp41: Acts as a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During fusion of viral and target intracellular membranes, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Complete fusion occurs in host cell endosomes and is dynamin-dependent, however some lipid transfer might occur at the plasma membrane. The virus undergoes clathrin-dependent internalization long before endosomal fusion, thus minimizing the surface exposure of conserved viral epitopes during fusion and reducing the efficacy of inhibitors targeting these epitopes. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm.

♦ Surface protein gp120: Virion membrane
♦ Peripheral membrane protein . Host cell membrane
♦ Peripheral membrane protein . Host endosome membrane
♦ Single-pass type I membrane protein . Note=The surface protein is not anchored to the viral envelope, but associates with the extravirion surface through its binding to TM. It is probably concentrated at the site of budding and incorporated into the virions possibly by contacts between the cytoplasmic tail of Env and the N-terminus of Gag. .
♦ Transmembrane protein gp41: Virion membrane
♦ Single-pass type I membrane protein . Host cell membrane
♦ Single-pass type I membrane protein . Host endosome membrane
♦ Single-pass type I membrane protein . Note=It is probably concentrated at the site of budding and incorporated into the virions possibly by contacts between the cytoplasmic tail of Env and the N-terminus of Gag. .

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