TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameDomainKingdom/PhylumProtein(s)
1.A.114.1.1









Plasma membrane proton-activated chloride channel, PACC1, or acid-sensitive outwardly-rectifying anion channel PAORAC/ASOR or TMEM206, of 350 aas and 2 TMSs.  Ion permeation-changing mutations along the length of TMS2 and at the end of TMS1 suggest that these segments line the pore. TMEM206 probably has orthologs in all vertebrates (Ullrich et al. 2019).  Knockout of mouse Pac abolished I Cl,H in neurons and attenuated brain damage after ischemic stroke (Yang et al. 2019). The cryoEM structure (3.1 Å resolution) in active and desensitized states has been determined (Wang et al. 2022).

Eukaryota
Metazoa
PACC1 of Homo sapiens
1.A.114.1.2









Proton-activated chloride channel of 298 aas and 2 TMSs. It mediates import of chloride ion in response to extracellular acidic pH (Yang et al. 2019) and displays channel activity with kinetic properties distinct from that of the human ortholog.

Eukaryota
Metazoa
TMEM206 of Danio rerio (Zebrafish) (Brachydanio rerio)
1.A.114.1.3









TMEM206 of 469 aas and 2 TMSs

Eukaryota
Opisthokonta
TMEM206 of Amphimedon queenslandica
1.A.114.1.4









TMEM206-like protein of 382 aas and 2 TMSs.

Eukaryota
Metazoa
TMEM206 of Saccoglossus kowalevskii
1.A.114.1.5









TMEM206 of 254 aas and 2 TMSs.

Eukaryota
Metazoa
TMEM206 of Callorhinchus milii
1.A.114.1.6









Proton-activated chloride channel of 351 aas and 2 TMSs near the N- and C-termini. TMEM206 is an evolutionarily conserved chloride channel that underlies ubiquitously expressed, proton-activated, outwardly rectifying, anion currents. Deng et al. 2021 reported the cryo-EM structure of pufferfish TMEM206, which forms a trimeric channel, with 6 TMSs, 2 per subunit, each with a large extracellular domain. An ample vestibule in the extracellular region is accessible laterally from the three side portals. The central pore contains multiple constrictions; a conserved lysine residue near the cytoplasmic end of the inner helix forms the presumed chloride ion selectivity filter. The core structure and assembly closely resemble those of the epithelial sodium channel/degenerin family of sodium channels that seem to be unrelated in amino acid sequence and conduct cations instead of anions. Together with electrophysiology, this structure provides insights into ion conduction and gating for these chloride channels (Deng et al. 2021).

Eukaryota
Opisthokonta
TMEM206 of Tetraodon nigroviridis (Spotted green pufferfish) (Chelonodon nigroviridis)