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J Gen Physiol February 1, 2016; 147 (2): 127-36.

Currents through Hv1 channels deplete protons in their vicinity.

De-la-Rosa V , Suárez-Delgado E , Rangel-Yescas GE , Islas LD .

Proton channels have evolved to provide a pH regulatory mechanism, affording the extrusion of protons from the cytoplasm at all membrane potentials. Previous evidence has suggested that channel-mediated acid extrusion could significantly change the local concentration of protons in the vicinity of the channel. In this work, we directly measure the proton depletion caused by activation of Hv1 proton channels using patch-clamp fluorometry recordings from channels labeled with the Venus fluorescent protein at intracellular domains. The fluorescence of the Venus protein is very sensitive to pH, thus behaving as a genetically encoded sensor of local pH. Eliciting outward proton currents increases the fluorescence intensity of Venus. This dequenching is related to the magnitude of the current and not to channel gating and is dependent on the pH gradient. Our results provide direct evidence of local proton depletion caused by flux through the proton-selective channel.

PubMed ID: 26809792
PMC ID: PMC4727945
Article link: J Gen Physiol

Species referenced: Xenopus laevis
Genes referenced: dbh hvcn1

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References [+] :
Baker, Genetically encoded fluorescent voltage sensors using the voltage-sensing domain of Nematostella and Danio phosphatases exhibit fast kinetics. 2012, Pubmed