A protein that has channel activity. Channel proteins enable energy-independent facilitated diffusion, mediated by passage of a solute through a transmembrane aqueous pore or channel. [ PRO:XQ http://amigo.geneontology.org/amigo/term/GO:0015267 ]
Synonyms: pore class transporter protein pore protein channel/pore class transporter protein fam:chan nonselective channel protein channel-forming toxin protein