| Primary Identifier | IPR044375 | Type | Domain |
| Short Name | Spike_S1_RBD_CoV_HKU1-like |
| description | The CoV Spike (S) protein is an envelope glycoprotein that plays the most important role in viral attachment, fusion, and entry into host cells, and serves as a major target for the development of neutralizing antibodies, inhibitors of viral entry, and vaccines. It is synthesised as a precursor protein that is cleaved into an N-terminal S1 subunit (~700 amino acids) and a C-terminal S2 subunit (~600 amino acids) that mediates attachment and membrane fusion, respectively. Three S1/S2 heterodimers assemble to form a trimer spike protruding from the viral envelope. The S1 subunit contains a receptor-binding domain (RBD), while the S2 subunit contains a hydrophobic fusion peptide and two heptad repeat regions. S1 contains two structurally independent domains, the N-terminal domain (NTD) and the C-terminal domain (C-domain). Depending on the virus, either the NTD or the C-domain can serve as the receptor-binding domain (RBD). Most CoVs, including SARS-CoV-2, SARS-CoV, and MERS-CoV use the C-domain to bind their receptors. However, CoV such as mouse hepatitis virus (MHV) uses the NTD to bind its receptor, mouse carcinoembryonic antigen related cell adhesion molecule 1a (mCEACAM1a). The S1 NTD contributes to the Spike trimer interface [, , , , ].This domain corresponds to the receptor binding domain (RBD) of the Spike S1 subunit from human coronavirus (CoV) HKU1, isolates N5 and N2. HKU1 is a human lineage A betacoronavirus that causes mild yet prevalent respiratory disease, and is related to the zoonotic SARS and MERS betacoronaviruses. These viruses use 9-O-acetyl-sialic acid (9-O-Ac-Sia) as a receptor which is terminally linked to oligosaccharides decorating glycoproteins and gangliosides at the host cell surface [, ]. |
