Recombinant Simian foamy virus Envelope glycoprotein gp130 (env)

The surface protein (SU) attaches the virus to the host cell by binding to the cell receptor. This interaction triggers the refolding of transmembrane protein (TM) and is thought to activate its fusogenic potential by unmasking its fusion peptide.; The transmembrane protein (TM) 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 viral and target cell membrane fusion, 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. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm.; The leader peptide is a component of released, infectious virions and is required for particle budding.