SARS-CoV-S

SARS-CoV spike protein

Spike glycoprotein
May down-regulate host tetherin (BST2) by lysosomal degradation, thereby counteracting its antiviral activity.
Attaches the virion to the cell membrane by interacting with host receptor, initiating the infection (By similarity).
Binding to human ACE2 and CLEC4M/DC-SIGNR receptors and internalization of the virus into the endosomes of the host cell induces conformational changes in the S glycoprotein. Proteolysis by cathepsin CTSL may unmask the fusion peptide of S2 and activate membrane fusion within endosomes.
Spike protein S2
Mediates fusion of the virion and cellular membranes by acting as a class I viral fusion protein. Under the current model, the protein has at least three 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.
Spike protein S2'
Acts as a viral fusion peptide which is unmasked following S2 cleavage occurring upon virus endocytosis.

Biological Process endocytosis involved in viral entry into host cellIEA:UniProtKB-UniRule
Biological Process fusion of virus membrane with host endosome membraneIEA:UniProtKB-UniRule
Biological Process fusion of virus membrane with host plasma membraneIEA:UniProtKB-UniRule
Biological Process membrane fusion1 PublicationIC:ComplexPortal
Biological Process positive regulation of viral entry into host cell1 PublicationIC:ComplexPortal
Biological Process receptor-mediated endocytosis of virus by host cellIC:ComplexPortal
Biological Process receptor-mediated virion attachment to host cellManual Assertion Based On ExperimentIDA:BHF-UCL
Biological Process suppression by virus of host tetherin activityIEA:UniProtKB-KW
Biological Process suppression by virus of host type I interferon-mediated signaling pathwayIEA:UniProtKB-KW
Biological Process viral entry into host cellIDA:ComplexPortal

Virion membrane
Host endoplasmic reticulum-Golgi intermediate compartment membrane
Host cell membrane
Accumulates in the endoplasmic reticulum-Golgi intermediate compartment, where it participates in virus particle assembly. Colocalizes with S in the host endoplasmic reticulum-Golgi intermediate compartment (PubMed:20861307).
Some S oligomers are transported to the host plasma membrane, where they may mediate cell-cell fusion.

Extracellular: 14-1195
Helical: 1196-1216
Cytoplasmic: 1217-1255

The cytoplasmic Cys-rich domain is palmitoylated. Spike glycoprotein is digested by cathepsin CTSL within endosomes.1 Publication
Specific enzymatic cleavages in vivo yield mature proteins. The precursor is processed into S1 and S2 by host cell furin or another cellular protease to yield the mature S1 and S2 proteins. Additionally, a second cleavage leads to the release of a fusion peptide after viral attachment to host cell receptor.
The cytoplasmic Cys-rich domain is palmitoylated. Spike glycoprotein is digested within host endosomes.