TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameDomainKingdom/PhylumProtein(s)
1.A.57.1.1









SARS-CoV Viroporin tetrameric ion channel. Protein 3a is of 274 aas and 3 TMSs. It activates the Nod-like receptor family members which are pyrin domain-containing 3 (NLRP3)proteins that regulate the secretion of proinflammatory cytokines such as interleukin 1 beta (IL-1beta) and IL-18. K+ efflux and mitochondrial reactive oxygen species are important for SARS-CoV 3a-induced NLRP3 inflammasome activation (Chen et al. 2019). Viroporin 3a exhibits allosteric properties (Tee et al. 2021).

Viruses
Nidovirales
SARS-Caronavirus
Viroporin
(Protein 3a)
(P59632)
1.A.57.1.2









Orf3 of 249 aas and 3 putative TMSs

Viruses
Nidovirales
Orf3 of Zaria bat coronavirus (F1BYM0)
1.A.57.1.3









The NS3 protein of 230aas and 3 N-terminal TMSs as well as 3 potential C-terminal TMSs of low hydrophobicity.

Viruses
Nidovirales
NS3 of Bat coronavirus HKU9-5-1 (E0ZN37)
1.A.57.1.4









Orf3 of 238aas and 3 putative TMSs

Viruses
Nidovirales
Orf3 of Eidolon bat coronavirus (F1DAZ2)
1.A.57.1.5









Orf3a of 275 aas and 3 central TMSs. Orf3a forms homodimers and homotetramers and is a non-selective catioin channel that is blocked by polycation channel inhibitors (Kern et al. 2021). They carry a PDZ-binding domain, lending them the versatility to interact with more than 400 target proteins in infected host cells. Structural considerations have been discussed (Barrantes 2021). Naturally occurring mutations in ORF3a are common and have been analyzed, and 28 fully concerved residues in 70,000 sequences that probably have structural or functional roles were also identified (Bianchi et al. 2020). Viroporin 3a exhibits allosteric properties (Tee et al. 2021). It has been implicated in apoptosis and inhibition of autophagy. The structure of the dimer has been determined at 2.1 Å resolution by cryoEM (Kern et al. 2021).

Viruses
Nidovirales
Orf3a of severe acute respiratory syndrome (SARS) coronavirus 2