Saccharomyces cerevisiae low affinity ammonium transporter Amf1p/YOR378W, aminotriazole resistance protein Atr1p, and similar transporters of the Major Facilitator Superfamily
Saccharomyces cerevisiae Amf1p/Ammonium Facilitator 1/YOR378W functions as a low affinity NH4+ transporter. S. cerevisiae aminotriazole resistance protein (Atr1p) is required for controlling sensitivity to aminotriazole; it is a putative component of the machinery responsible for pumping aminotriazole (and possibly other toxic compounds) out of the cell. This subfamily also includes S. cerevisiae YMR279C, a putative boron transporter involved in boron efflux and resistance, and Kluyveromyces lactis Knq1p which is involved in oxidative stress response and iron homeostasis. Amf1p, Atr1p, and YMR279C have been classified as group 1 members of the DHA2 (Drug:H+ Antiporter family 2) family, K. lactis Knq1 as group 2. This subfamily also includes two Aspergillus terreus terrein biosynthesis cluster proteins, efflux pump TerG and TerJ which may be required for efficient secretion of terrein or other secondary metabolites produced by the terrein gene cluster. The Amf1p-like subfamily belongs to the Methylenomycin A resistance protein (also called MMR peptide) and similar multidrug resistance (MDR) transporters (MMR-like MDR transporter) family of the Major Facilitator Superfamily (MFS) of transporters. MFS proteins are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
Feature 1:putative chemical substrate binding pocket [chemical binding site]
Evidence:
Comment:based on the structures of MFS transporters with bound substrates, substrate analogs, and/or inhibitors
Comment:since MFS proteins facilitate the transport of many different substrates including ions, sugar phosphates, drugs, neurotransmitters, nucleosides, amino acids, and peptides, the residues involved in substrate binding may not be strictly conserved among superfamily members
Comment:the substrate binding site or translocation pore has access to both sides of the membrane in an alternating fashion through a conformational change of the MFS transporter
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