TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameDomainKingdom/PhylumProtein(s)
*1.A.11.1.1









Ammonia transporter and regulatory sensor, AmtB (Blauwkamp and Ninfa, 2003; Khademi et al., 2004)

Bacteria
Proteobacteria
AmtB of E. coli (P69681)
*1.A.11.1.2









High affinity ammonia/methylammonia uptake carrier, Amt1 or AmtA (Walter et al., 2008)
Bacteria
Actinobacteria
Amt1 of Corynebacterium glutamicum (P54146)
*1.A.11.1.3









Low affinity (KM > 3mM) ammonia uptake carrier, AmtB (Walter et al., 2008)
Bacteria
Actinobacteria
AmtB of Corynebacterium glutamicum (Q79VF1)
*1.A.11.1.4









Ammonia channel protein, AmtB (forms a ternary complex with the trimeric PII protein, GlnZ (AAG10012) and the nitrogenous regulatory glycohydrolase enzyme, DraG, causing DraG sequestration and N2ase regulation (Huergo et al., 2007)
Bacteria
Proteobacteria
AmtB of Azospirillum brasilense (P70731)
*1.A.11.1.5









Ammonia channel (Ammonia transporter)
Bacteria
Aquificae
Amt of Aquifex aeolicus
*1.A.11.2.1









High-affinity electrogenic ammonia/methylammonia transporter (allosterically activated by the C-terminus (Loqué et al., 2009).  NH4+ is stable in the AmtB pore, reaching a binding site from which it can spontaneously transfer a proton to a pore-lining histidine residue (His168). The substrate diffuses down the pore in the form of NH3, while the proton is cotransported through a highly conserved hydrogen-bonded His168-His318 pair (Wang et al. 2012).

Eukaryota
Viridiplantae
Amt1 of Arabidopsis thaliana (P54144)
*1.A.11.2.2









Ammonia-specific uptake carrier, Amt2. For AMT2 from Arabidopsis thaliana NH4+ is the recruited substrate, but the uncharged form NH3 is conducted.  AtAMT2 partially co-localizes with electrogenic AMTs and conducts methylamine with low affinity (Neuhäuser et al., 2009). This may explain the different capacities of AMTs to accumulate ammonium in the plant cell.

Eukaryota
Viridiplantae
Amt2 of Arabidopsis thaliana
*1.A.11.2.3









High-affinity ammonia/methylammonia transporter, Amt1(Paz-Yepes et al., 2007)
Bacteria
Cyanobacteria
Amt1 of Synechococcus elongatus sp. PCC7942 (Q93IP6)
*1.A.11.2.4









High-affinity ammonia/methylammonia transporter, LeAMT1;1
Eukaryota
Viridiplantae
LeAMT1;1 of Lycopersicon esculentum (P58905)
*1.A.11.2.5









Ammonium/methyl ammonium uptake permease, AmtB (may need AmtB to concentrate [14C]methyl ammonium (Paz-Yepes et al., 2007))

Bacteria
Cyanobacteria
AmtB of Synechococcus sp CC9311 (Q0IDE4)
*1.A.11.2.6









Pollen-specific, plasma membrane, high affinity (17μM) ammonium uptake transporter, Amt1;4 (Yuan et al., 2009) (most similar to 1.A.11.2.1).
Eukaryota
Viridiplantae
Amt1;4 of Arabidopsis thaliana (Q9SVT8)
*1.A.11.2.7









Amt2 NH4+/CH3-NH3+ transporter, subject to allosteric activation by a C-terminal region (Loqué et al., 2009).

Archaea
Euryarchaeota
Amt2 of Archaeoglobus fulgidus (O28528)
*1.A.11.2.8









Amt1;1, a proposed NH4+:H+ sumporter (Ortiz-Ramirez et al., 2011)

Eukaryota
Viridiplantae
Amt1;1 of Phaseolus vulgaris (E2CWJ2)
*1.A.11.2.9









Ammonium transporter 2, AmtB

Eukaryota
Dictyosteliida
AmtB of Dictyostelium discoideum
*1.A.11.2.10









Putative ammonium transporter 2
Eukaryota
Metazoa
amt-2 of Caenorhabditis elegans
*1.A.11.2.11









Ammonium transporter, AmtB or Amt1 of 463 aas and 9 TMSs.  Regulated by direct interaction with GlnK (Pedro-Roig et al. 2013).

Archaea
Euryarchaeota
AmtB of Haloferax mediterranei (Halobacterium mediterranei)
*1.A.11.2.12









Ammonium uptake transporter, Amt1 of 458 aas and 11 TMSs.  62% identical to Amt1 of Pyropia yezoensis (Rhodophyta) which is 483 aas long with 11 TMSs and is induced by nitrogen deficiency (Kakinuma et al. 2016).

Eukaryota
Florideophyceae
Amt1 of Chondrus crispus (Carrageen Irish moss) (Polymorpha crispa)
*1.A.11.2.13









High affinity (~50 mμM) ammonium transporter, Amt1.3 of 498 aas and 10 TMSs (Loqué et al. 2006). The tobacco orthologue, of 464 aas and 10 TMSs, NtAMT1.3, is present in roots and leaves and faciltates NH4+ entry. It is up regulated upon nitrogen starvation (Fan et al. 2017).

Ant1.3 of Arabidopsis thaliana (Mouse-ear cress)
*1.A.11.3.1









Low-affinity ammonia transporter, Mep1 (Has a pair of conserved his/glu residues; Boeckstaens et al., 2008)
Eukaryota
Fungi
Mep1 of Saccharomyces cerevisiae (P40260)
*1.A.11.3.2









High-affinity ammonia transporter and sensor, Mep2 (also an NH4+ sensor) (Javelle et al., 2003a; Rutherford et al., 2008) (has a pair of conserved his/his residues; mutation to his/glu as in Mep1 leads to uncoupling of transport and sensor functions (Boeckstaens et al., 2008))
Eukaryota
Fungi
Mep2 of Saccharomyces cerevisiae (P41948)
*1.A.11.3.3









High affinity ammonia/methylamine transporter, Amt1 (may also serve as a sensor) (Javelle et al., 2003b)
Eukaryota
Fungi
Amt1 of Hebeloma cylindrosporum (Q8NKD5)
*1.A.11.3.4









Low affinity ammonia transporter, Amt2 (Javelle et al., 2001, 2003b)
Eukaryota
Fungi
Amt2 of Hebeloma cylindrosporum (Q96UY0)
*1.A.11.3.5









The Mep2 ammonium transporter 60% identical to the S. cerevisiae Mep2 (1.A.11.3.2). (Distinct residues mediate transport and signaling; Dabas et al., 2009).
Eukaryota
Fungi
Mep2 of Candida albicans (Q59UP8)
*1.A.11.4.1









Rhesus (Rh) type C glycoprotein NH3/NH4+ transporter, RhCG (also called tumor-related protein DRC2) (Bakouh et al., 2004; Worrell et al., 2007). Zidi-Yahiaoui et al. (2009) have described characteristics of the pore/vestibule. The structure is known to 2.1 Å resolution (Gruswitz et al., 2010). Each monomer contains 12 transmembrane helices, one more than in the bacterial homologs. Reconstituted into proteoliposomes, RhCG conducts NH3 to raise the internal pH. Models of the erythrocyte Rh complex based on the RhCG structure suggest that the erythrocytic Rh complex is composed of stochastically assembled heterotrimers of RhAG, RhD, and RhCE (Gruswitz et al., 2010).

Eukaryota
Metazoa
RhCG of Homo sapiens (Q9UBD6)
*1.A.11.4.2









Rhesus (Rh) type B glycoprotein NH3/NH4+ transporter, RhBG (~50% identical to type C) (Lopez et al., 2005; Worrell et al., 2008). Electrogenic NH4+ transport is stimulated by alkaline pH(out) but inhibited by acidic pH(out) (Nakhoul et al., 2010). Regulated by Wnt/β-catenin signalling, a pathway frequently deregulated in many cancers and associated with tumorigenesis (Merhi et al. 2015).

Eukaryota
Metazoa
RhBG of Homo sapiens (Q9H310)
*1.A.11.4.3









Rhesus (Rh) complex (tetramer: RhAG2, RhCE1, RhD1) of 409 aas and 12 TMSs. Exports ammonia from human red blood cells (Conroy et al., 2005). RhAG is also called RH50.  RhAG variants (I61R, F65S), associated with overhydrated hereditary stomatocytosis (OHSt), a disease affecting erythrocytes, are alterred for bidirectional ammonium transport (Deschuyteneer et al. 2013).  The system transports ammonia, methylammonia, ethylammonia and fluoroethylamine.  19F-fluoroethylamine has been used to study rapid transport as its NMR spectra are different inside and outside of human red blook cells (Szekely et al. 2006).

Eukaryota
Metazoa
The RhAG/RhCE/RhD, complex of Homo sapiens
RhAG (Q02094)
RhCE (P18577)
RhD (Q02161)
*1.A.11.4.4









The RH50 NH3 channel (most like human Rh proteins TC# 1.A.11.4.1 and 2; 36-38% identity) (Cherif-Zahar et al., 2007). The Rh CO2 channel protein (3-D structure ± CO2 available) (3B9Z_A; 3B9Y_A) (Li et al., 2007; Lupo et al., 2007) (also transports methyl ammonia) (Weidinger et al., 2007).

Bacteria
Proteobacteria
RH50 of Nitrosomonas europaea (Q82X47)  
*1.A.11.4.5









Kidney rhesus glycoprotein p2 (Rhp 2). Transports NH3 and methylammonium (Nakada et al., 2010).

Eukaryota
Metazoa
Rhp2 of Triakis scyllium (D0VX38)
*1.A.11.4.6









Rhesus-like glycoprotein A (Rh50-like protein RhgA)

Eukaryota
Dictyosteliida
RhgA of Dictyostelium discoideum
*1.A.11.4.7









Ammonium transporter of 391 aas and 12 TMSs.  Shows limited seqences similarity with 9.B.124.1.7 (e-5) (residues 1-5 align with residues 4 - 8 in 9.B.124.1.7).

Bacteria
Firmicutes
Ammonium transporter of [Clostridium] papyrosolvens
*1.A.11.4.8









NH3 (NH4+) transporting Rhesus glycoprotein, Rhag, of 437 aas and 11 TMSs.  Induced by ammonia exposure in the apical membrane of gill epithelia (Chen et al. 2017).

Eukaryota
Metazoa
Rhag of Anabas testudineus (climbing perch)
*1.A.11.4.9









NH3 (NH4+) transporting Rhesus glycoprotein, Rhcg2, of 482 aas and 11 TMSs.  Induced by ammonia exposure in the basolateral membrane of gill epithelia (Chen et al. 2017).

Bacteria
Proteobacteria
Rhcg2 of Anabas testudineus (climbing perch)
*1.A.11.5.1









Trimeric ammonia channel protein, Amt-1 (391 aas)
Archaea
Euryarchaeota
Amt-1 of Archaeoglobus fulgidus (O29285)
*1.A.11.5.2









The ammonium transporter channel, AmtA (regulates NH3 homeostasis during growth and development (Yoshino et al., 2007).
Eukaryota
Dictyosteliida
AmtA of Dictyostelium discoideum (Q9BLG4)