Ammonium transporter (AMT (for plant and bacterial forms), also known as Rh for mammalian forms)

Ammonium transporters are a family of integral membrane proteins found across all domains of life—including bacteria, plants, and animals—that are essential for the uptake, distribution, and regulation of ammonium, a key nitrogen source[1][2][3][5][7][8]. These proteins include Amt proteins in bacteria and plants and the Rh (Rhesus) proteins in mammals, and exist as homotrimers with each monomer forming a hydrophobic channel for ammonia/ammonium conduction[1][3][5]. The transport mechanism varies: bacteria and plants often move ammonium directly or as ammonia, while mammals transport ammonia via Rh glycoproteins, which are critical for renal acid-base regulation[2][3]. In plants, ammonium transporters mediate both nutrient uptake and stress adaptation (e.g., in drought or salt stress)[4][5]. Regulation occurs at both transcriptional and post-translational levels, often involving protein-protein interactions (e.g., GlnK/PII proteins regulate AmtB in bacteria)[1][2][4]. Dysfunction or mutations in human Rh ammonia transporters are implicated in certain metabolic or kidney diseases, but no approved drugs are known to selectively target these proteins[8]. The ammonium transporter family is thus a fundamental membrane transporter class critical for nitrogen metabolism and homeostasis in diverse life forms[6][7].

Other names

Ammonia transporterAmmonium transporter/Methylammonium permease (Mep)Rh glycoproteinAmt proteinAMT familyRhbgRhcgAmtB

Facilitates transport of ammonia (NH₃) or ammonium ion (NH₄⁺) across cellular membranes, via a hydrophobic transmembrane pore that allows passage of neutral ammonia or, depending on the organism, cotransport/antiport with H⁺