| Hauptseite > Publikationsdatenbank > A large family of unusual voltage‐sensing proton channels (Hv3) in mollusks |
| Journal Article | FZJ-2026-04932 |
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2026
Wiley-Blackwell
Oxford [u.a.]
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Please use a persistent id in citations: doi:10.1111/febs.70617
Abstract: Mollusks exhibit an unusually high diversity of genes encodingvoltage-gated proton channel homologs. In addition to the conventionalproton channels Hv1, Hv2, and Hv4, a structurally and functionally atypicalproton channel was previously identified in Aplysia californica (AcHv3,subsequently renamed AcHv3.1). A comprehensive analysis of cDNA, transcriptomeshotgun assembly (TSA) and genomic databases revealed numerousorthologous and paralogous Hv3-like sequences in Aplysia and acrossall other molluscan species analyzed. These Hv3-like channels share canonicalfeatures of voltage-gated proton channels, including four transmembranespanning segments (S1–S4), a negatively charged residue in S1responsible for proton selectivity, a conserved voltage-sensing motif in S4containing positively charged arginine residues and a fully conserved tryptophanresidue. However, Hv3-like channels differ markedly from conventionalHv channels in possessing much larger intracellular N- andC-terminal domains, an elongated extracellular loop between S1 and S2and a reduced number of gating charges in S4, with only two arginine residues(or a single arginine in the case of Hv3.6 channels) compared to threein canonical Hv channels. In addition, Hv3-like channels contain a uniqueproline residue within S4, forming a characteristic PWRxxR motif. Basedon structural differences, including putative PDZ-Binding motifs and spacingof transmembrane cysteine residues, together with molecular distancetree analyses, a classification into seven subfamilies (Hv3.1-Hv3.7) is proposed.Some of these subfamilies were found only in Gastropoda or Bivalvia,while others were identified in all molluscan classes. AlthoughGFP-tagged AcHv3.1, AcHv3.2, and AcHv3.5 localized to the plasmamembrane, only AcHv3.1 generated detectable proton currents.
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