<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 ammonia/ammonium. Ammonia is an excellent nitrogen source for many bacteria, fungi, and plants, but it can be cytotoxic, especially for animal cells at high concentration. Its transport across cellular membranes is thus of high biological relevance. Ammonia (NH3) is a weak base and exists predominantly as the ammonium ion (NH4+) in biological fluids.