<p>An evidence describes the source of an annotation, e.g. an experiment that has been published in the scientific literature, an orthologous protein, a record from another database, etc.</p>
Protein involved in the transport of ions. Such proteins are usually transmembrane and mediate a movement of ions across cell membranes. Transport may be passive (facilitated diffusion; down the electrochemical gradient), or active (against the electrochemical gradient). Active transport requires energy which may come from light, oxidation reactions, ATP hydrolysis, or cotransport of other ions or molecules.