monoatomic cation channel activity proton transmembrane transporter activity proton channel activity https://github.com/geneontology/go-ontology/issues/27278 Enables the facilitated diffusion of a hydrogen ion (by an energy-independent process) involving passage through a transmembrane aqueous pore or channel without evidence for a carrier-mediated mechanism. hydrogen ion channel activity Reactome:R-HSA-9729542 molecular_function GO:0015252