Envelope glycoprotein gp160 - P03377 (ENV_HV1BR)


Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for P03377: 10
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. (data source: UniProt  )
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. (data source: UniProt  )
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. (data source: UniProt  )
Subunit structure
The mature envelope protein (Env) consists of a homotrimer of non-covalently associated gp120-gp41 heterodimers. The resulting complex protrudes from the virus surface as a spike. There seems to be as few as 10 spikes on the average virion. Surface protein gp120 interacts with human CD4, CCR5 and CXCR4. Gp120 also interacts with the C-type lectins CD209/DC-SIGN and CLEC4M/DC-SIGNR (collectively referred to as DC-SIGN(R)). Gp120 and gp41 interact with GalCer. Gp120 interacts with human ITGA4/ITGB7 complex; on CD4+ T-cells, this interaction results in rapid activation of integrin ITGAL/LFA-1, which facilitate efficient cell-to-cell spreading of HIV-1. Gp120 interacts with cell-associated heparan sulfate; this interaction increases virus infectivity on permissive cells and may be involved in infection of CD4- cells. (data source: UniProt  )
Some of the most genetically diverse regions of the viral genome are present in Env. They are called variable regions 1 through 5 (V1 through V5). Coreceptor usage of gp120 is determined mainly by the primary structure of the third variable region (V3) in the outer domain of gp120. The sequence of V3 determines which coreceptor, CCR5 and/or CXCR4 (corresponding to R5/macrophage, X4/T cell and R5X4/T cell and macrophage tropism), is used to trigger the fusion potential of the Env complex, and hence which cells the virus can infect. Binding to CCR5 involves a region adjacent in addition to V3. (data source: UniProt  )
This protein in other organisms (by gene name):
Organism (common name): isolate HXB3
Other Gene name: env
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The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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