NTR: intracellular calcium activated hydrogencarbonate channel activity

[Argoudpuy]

Please provide as much information as you can:

• Suggested term label: ~intracellular calcium activated hydrogencarbonate channel activity~ calcium-activated bicarbonate channel activity

• Definition (free text) Enables the transmembrane transfer of hydrogencarbonate by a channel that opens in response to stimulus by calcium ions. Transport by a channel involves catalysis of facilitated diffusion of a solute (by an energy-independent process) involving passage through a transmembrane aqueous pore or channel, without evidence for a carrier-mediated mechanism.

• **Reference, in format PMID:18400985 (REQUIRED)

• Gene product name and ID to be annotated to this term

• Parent term(s) intracellular hydrogencarbonate channel activity

• Children terms (if applicable) Should any existing terms that should be moved underneath this new proposed term?

• Synonyms (please specify, EXACT, BROAD, NARROW or RELATED) intracellular calcium activated bicarbonate channel activity

• Cross-references

• For enzymes, please provide RHEA and/or EC numbers.

• Can also provide MetaCyc, KEGG, Wikipedia, and other links.

• Any other information

[pgaudet]

Hi @Argoudpuy

Is this 'intracellularly gated'? (like GO:0099142 'intracellularly ATP-gated ion channel activity'); otherwise we dont capture the CC in the MF term.

Also, I dont see the Ca-gated aspect in the paper you cite; are there other papers we can use to support that ?

[Argoudpuy]

Hi @pgaudet, bestrophins are activated by a cytoplasmic [Ca2+] increase then they are intracellular gated.

Effectively the Ca2+dependence is not shown, there are no experiment where the HCO3- currents were recorded without Ca2+. But in Fig. 1. they say that cells were stimulated by ramp voltages, and Cl- currents were recorded with pipette solution containing high Ca2+ (see MATERIALS AND METHODS). For measurement of bestrophin permeabilities to HCO3- relative to Cl-, 140 mM NaCl in bath solution was replaced with 140 mM NaHCO3, I can assum that HCO3- currents were also recorded with pipette solution containing high Ca2+ (see MATERIALS AND METHODS). In addition, in the discussion, they assume that both Cl- and HCO3- conductances require intracellular Ca2+ in order for the conductance to be turned on. I hope that help thanks