Protein Domain : Structural accessory protein ORF7a, SARS-CoV-2-like IPR044390

Type	Family
Description	SARS-CoV contains a number of open reading frames that code for a total of eight accessory proteins, namely ORFs 3a, 3b, 6, 7a, 7b, 8a, 8b, and 9b. These ORFs are specific for SARS-CoV and do not show significant homology to accessory proteins of other coronaviruses. This entry represents the structural accessory protein ORF7a, also called NS7a, of Severe Acute Respiratory Syndrome Coronaviruses (SARS-CoV) from betacoronavirus subgenera Sarbecovirus (lineage B), including SARS-CoV-2. ORF7a/NS7a from betacoronavirus in the subgenera Sarbecovirus (B lineage) are not related to NS7a proteins from other coronavirus lineages. Structurally, ORF7a possesses a distinctive immunoglobulin (Ig)-like domain which is related to extracellular metazoan Ig domains that are involved in adhesion, such as ICAM; it also contains a 15-aa signal peptide sequence at its N terminus, an 81-aa luminal domain, a 21-aa transmembrane domain, and a short C-terminal tail. Coexpression of SARS-CoV ORF7a with S, M, N, and E proteins resulted in production of virus-like particles (VLPs) carrying ORF7a protein, indicating that ORF7a is a viral structural protein. Expression studies of ORF7a have shown that biological functions include induction of apoptosis through a caspase-dependent pathway, activation of the p38 mitogen-activated protein kinase signaling pathway, inhibition of host protein translation, and suppression of cell growth progression. These results collectively suggested that ORF7a protein may be involved in virus-host interactions []. Studies in SARS-CoV-2 revealed that ORF7a plays a role as antagonist of host tetherin (BST2), disrupting its antiviral effect. ORF7a binds to BST2 and sequesters it to the perinuclear region, thereby preventing its antiviral function at cell membrane [].
Short Name	ORF7a_SARS-CoV-2-like