TCID | Name | Domain | Kingdom/Phylum | Protein(s) |
---|---|---|---|---|
2.A.19.1.1 | Ca2+:H+ antiporter (also catalyzes Na+:H+ and K+:H+ antiport in processes that have been shown to be physiologically important under certain conditions) (Ivey et al., 1993; Radchenko et al., 2006) | Bacteria |
Pseudomonadota | ChaA of E. coli |
2.A.19.2.1 | Ca2+:H+ antiporter | Bacteria |
Cyanobacteriota | Ca2+:H+ antiporter of Synechocystis |
2.A.19.2.2 | Vacuolar [Mn2+ or Ca2+]:H+ antiporter, Hum1 (Mn2+ resistance (Mnr1)) protein. Vcx1 has 11 probable TMSs with the N-terminus inside (Segarra and Thomas, 2008). The 3-d structure has been determined at 2.3 Å resolution for the cytosolic facing, substrate bound form, favoring the alternating access mechanism of transport (Waight et al. 2013). | Eukaryota |
Fungi, Ascomycota | Hum1 (Mnr1) of Saccharomyces cerevisiae |
2.A.19.2.3 | High affinity vacuolar (tonoplast) Ca2+:H+ antiporter (also exports Cd2+ and Zn2+; Shigaki et al., 2005) It is expressed in leaves (Cheng et al., 2005). It determines sensitivity to abscisic acid and sugars during germination and tolerance to ethylene during early seedling development (Zhao et al., 2008). BrCAX1 is involved in Ca2+ transport and Ca2+ deficiency-induced tip-burn in chinese cabbage (Brassica rapa L. ssp. pekinensis) (Cui et al. 2023). | Eukaryota |
Viridiplantae, Streptophyta | Cax1 of Arabidopsis thaliana |
2.A.19.2.4 | Low affinity Ca2+:H+/heavy metal cation (e.g., Mn2+, Mg2+, Cd2+, Ca2+):H+ antiporter, Cax2. The apple (Malus domestiga) ortholog (CAX2L-2) functions positively in modulation of Ba2+ tolerance (Mei et al. 2023). | Eukaryota |
Viridiplantae, Streptophyta | Cax2 of Arabidopsis thaliana |
2.A.19.2.5 | High affinity vacuolar (tonoplast) Ca2+:H+ antiporter (also exports Cd2+ and Zn2+; Shigaki et al., 2005) highly expressed in roots (Cheng et al., 2005) (exhibits phenotypes characteristic of CAX1, but also determines sensitivities to salt, lithium and low pH (Zhao et al., 2008) | Eukaryota |
Viridiplantae, Streptophyta | Cax3 of Arabidopsis thaliana
(Q93Z81) |
2.A.19.2.6 | Algae Ca2+: H+ and Na+:H+ exchanger, CAX1 (mediates stress responses to high Ca2+, Na+ and Co2+). | Eukaryota |
Viridiplantae, Chlorophyta | CAX1 of Chlamydomonas reinhardtii (B6ZCF4) |
2.A.19.2.7 | Ca2+/H+ antiporter, YfkE (Fujisawa et al., 2009). YfkE is a homotrimer with a subunit size of 451 aas. The 3-d x-ray strcuture is known to 3.1 Å resolution (Wu et al. 2013). The conformational transition is triggered by the rotation of the kink angles of transmembrane helices 2 and 7 and is mediated by large conformational changes in their adjacent transmembrane helices 1 and 6. The inward facing conformation contrasts with the outward facing conformation demonstrated for NCX_Mj (TC# 2.A.19.5.3). The inward facing conformation has a "hydrophobic seal" that closes the external exit (Wu et al. 2013). Intracellular Ca2+ regulation of this H+/Ca2+ antiporter is mediated by a Ca2+ mini-sensor (Lu et al. 2020). | Bacteria |
Bacillota | YfkE of Bacillus subtilis (O34840) |
2.A.19.2.8 | The vacuolar Ca2+:H+ exchanger, CAX (Bowman et al., 2011). | Eukaryota |
Fungi, Ascomycota | CAX of Neurospora crassa (O59940) |
2.A.19.2.9 | Vacuolar cation:proton exchanger, Cax4 (transports Cd2+>Zn2+>Ca2+>Mn2+) (Cheng et al., 2002; Mei et al., 2009). The rice orthologue, Cax4, may transport Ca2+, Mn2+ and Cu2+, and functions in salt stress (Yamada et al. 2014). The A. thaliana protein contributes to Cd2+ resistance (Liao et al. 2019). | Eukaryota |
Viridiplantae, Streptophyta | Cax4 of Arabidopsis thaliana (Q945S5) |
2.A.19.2.10 | Vacuolar cation/proton exchanger 1a (Ca(2+)/H(+) exchanger 1a) (OsCAX1a) | Eukaryota |
Viridiplantae, Streptophyta | CAX1a of Oryza sativa subsp. japonica |
2.A.19.2.11 | The Ca2+:H+ antiporter, YfkE; homotrimer with subunit size of 451 aas. The 3-d x-ray strcuture is known to 3.1 Å resolution (Wu et al. 2013). The conformational transition is triggered by the rotation of the kink angles of transmembrane helices 2 and 7 and is mediated by large conformational changes in their adjacent transmembrane helices 1 and 6. The inward facing conformation contrasts with the outward facing conformation demonstrated for NCX_Mj (TC# 2.A.19.5.3). The inward facing conformation has a "hydrophobic seal" that closes the external exit. | Bacteria |
Bacillota | YfkE of Bacillus subtilis |
2.A.19.2.12 | Ca2+/Mg2+/Mn2+:H+ antiporter, CAX or CHA, of 441 aas with a 90 residue hydrophilic N-terminus followed by 11 TMSs (Wunderlich 2022). | Eukaryota |
Apicomplexa | CAX of Plasmodium falciparum |
2.A.19.3.1 | The 10 TMS cardiac Ca2+:3 Na+ antiporter, NCX1 (Ren and Philipson 2013). The Ca2+ sensor (residues 371-508) binds cytoplasmic Ca2+ allosterically to activate exchange activity) (Nicoll et al., 2006; Ren et al., 2006) NCX1 forms homodimers (Ren et al., 2008). It is present in mitochondria where it catalyzes Ca2+ efflux. TMS packing has been analyzed by Ren et al. (2010). Cytoplasmic Ca2+ regulates the dimeric NCX by binding to two adjacent Ca2+-binding domains (CBD1 and CBD2) located in the large intracellular loop between transmembrane segments 5 and 6. John et al. (2011) showed that Ca2+decreases the distance between the cytoplasmic loops of NCX pairs, thereby activating transport. Ser110 in TMS2 plays a role in both Na+ and Ca2+ transport (Ottolia and Philipson 2013). nimodipiine-sensitive NCX1, as well as mitochondrial Ca2+ uptake, plays an important role in clearing somatic Ca2+ after depolarization-induced Ca2+ influx in SCN neurons (Wang et al. 2015). Regulation in suprachiasmatic nucleus neurons has been studied (Cheng et al. 2018). Genetic knockout and pharmacologic inhibitors of NCX1 attenuate hypoxia-induced pulmonary arterial hypertension (Nagata et al. 2020). The main Na+ influx pathway in myocardia in neonates is the NCX transporter (Oshiyama et al. 2022). Cytosolic Ca2+ and Na+ allosterically regulate Na+/Ca2+ exchanger (NCX) proteins to vary the NCX-mediated Ca2+ entry/exit rates in diverse mammalian cell types (Giladi et al. 2024). | Eukaryota |
Metazoa, Chordata | Ca2+ regulated Ca2+:Na+ antiporter (NCX1) of Bos taurus |
2.A.19.3.2 | Probable Ca2+:3Na+ antiporter, Calx (contains two repeat motifs Calx-α and Calxβ, between the two transmembrane domains, as is true of many Ca2+:Na+ antiporters (Schwarz and Benzer, 1997). CALX activity is inhibited by Ca2+ interaction within its two intracellular Ca2+ regulatory domains CBD1 and CBD2. The Ca2+ inhibition of CALX is achieved by interdomain conformational changes induced by Ca2+ binding at CBD1 (Wu et al., 2011). The exchanger is an essential Ca2+ extrusion mechanism in excitable cells. It consists of a transmembrane domain and a large intracellular loop that contains the two Ca2+-binding domains, CBD1 and CBD2 (de Souza Degenhardt et al. 2021). The two CBDs are adjacent to each other and form a two-domain Ca2+ sensor called CBD12. Binding of intracellular Ca2+ to CBD12 activates NCX but inhibits the NCX of Drosophila, CALX. CALX and NCX CBD12 constructs display interdomain flexibility in the apo state but assume rigid interdomain arrangements in the Ca2+-bound state. CALX-CBD12 preferentially samples closed conformations, whereas the wide-open interdomain arrangement, characteristic of the Ca2+-bound state, is less frequently sampled. These results are consistent with the view that Ca2+ binding shifts the CBD12 conformational ensemble toward extended conformers, which could be a key step in the NCXs' allosteric regulation mechanism (de Souza Degenhardt et al. 2021). | Eukaryota |
Metazoa, Arthropoda | Calx of Drosophila melanogaster (O18367) |
2.A.19.3.3 | Plasma membrane sodium:calcium exchanger, NCX3, NAC3 or SLC8A3, controlling Ca2+ homeostasis. Extrudes 1 Ca2+ for 3 extracellular Na+ ions. Potent inhibitors have been identified (Secondo et al. 2015). One such inhibitor of NCX transporters, ORM-10962, exhibits high efficacy and selectivity. Selective NCX inhibition can exert positive as well as negative inotropic effects, depending on the actual operation mode of the NCX (Kohajda et al. 2016). Bepridil is a commonly used medication for arrhythmia and heart failure. It primarily exerts hemodynamic effects by inhibiting Na+/K+ movement and regulating Na+/Ca2+ exchange (Wei et al. 2022). | Eukaryota |
Metazoa, Chordata | SLC8A3 of Homo sapiens |
2.A.19.3.4 | Sodium/calcium exchanger 1 (Na+/Ca2+-exchange protein 1), CNC NCX1 of 973 aas and 12 TMSs in a 6 + 6 TMS arrangement. The cardiac isoform, CAX1.1, like the archaeal homologues for which high resolution 3-d structures are available (TC#s 2.A.19.5.3 and 2.A.19.8.2), have two aqueous ion permeation channels with cavities that can face the cytoplasm or the external medium (John et al. 2013). It exchanges one Ca2+ ion against three to four Na+ ions, and thereby contributes to the regulation of cytoplasmic Ca2+ levels and Ca2+-dependent cellular processes (Komuro et al. 1992; , Van Eylen et al. 2001; Kofuji et al. 1992). It also contributes to Ca2+ transport during excitation-contraction coupling in muscle. In a first phase, voltage-gated channels mediate the rapid increase of cytoplasmic Ca2+ levels due to release of Ca2+ stores from the endoplasmic reticulum. SLC8A1 mediates the export of Ca2+ from the cell during the next phase, so that cytoplasmic Ca2+ levels rapidly return to baseline. It is also required for normal embryonic heart development and the onset of heart contractions. Both NCX1 and NCX2 play important roles in the motility of the gastric fundus, ileum and distal colon (Nishiyama et al. 2016). An amphipathic α-helix in the NCX1 large intracellular loop controls NCX1 palmitoylation. Thus, NCX1 palmitoylation is governed by a distal secondary structure element rather than by local primary sequence (Plain et al. 2017). The anti-aging gene NM_026333 contributes to proton-induced aging via the NCX1-pathway (Osanai et al. 2018). Dynamic palmitoylation modulates its structure, affinity for lipid-ordered domains, and inhibition by XIP (Gök et al. 2020). Na+/Ca2+ exchanger, NCX1, and canonical transient receptor potential channel 6 (TRPC6) are recruited by STIM1 to mediate Store-Operated Calcium Entry in primary cortical neurons (Tedeschi et al. 2022). SEA0400 is a potent and selective Na+/Ca2+ exchanger (NCX) inhibitor (Iwamoto et al. 2004). Along the proximal tubule and thick ascending limb of the kidney, Ca2+ and Na+ transport occur in parallel, but those processes were dissociated in the distal convoluted tubule (Hakimi et al. 2023). Xue et al. 2023 presented cryo-EM structures of human cardiac NCX1 in both inactivated and activated states, elucidating key structural elements important for NCX ion exchange and its modulation by cytosolic Ca2+ and Na+. They showed that the interactions between the ion-transporting transmembrane (TM) domain and the cytosolic regulatory domain define the activity of NCX. In the inward-facing state with low cytosolic [Ca2+], a TM-associated four-stranded beta-hub mediates tight packing between the TM and cytosolic domains, resulting in the formation of a stable inactivation assembly that blocks the TM movement required for ion exchange. Ca2+ binding to the cytosolic second Ca2+-binding domain (CBD2) disrupts this inactivation assembly which releases its constraint on the TM domain, yielding an active exchanger. Thus, the NCX1 structures provide an essential framework for the mechanistic understanding of the ion transport and cellular regulation of NCX family proteins (Xue et al. 2023). Structural insight into the allosteric inhibition of human sodium-calcium exchanger NCX1 by XIP and SEA0400 have been published (Dong et al. 2024). The cryo-EM structure of NCX1.3 in the presence of a specific inhibitor, SEA0400 shows that conserved ion-coordinating residues are exposed on the cytoplasmic face of NCX1.3, indicating that the observed structure is stabilized in an inward-facing conformation. The regulatory calcium-binding domains (CBDs) assemble with the ion-translocation transmembrane domain (TMD). The exchanger-inhibitory peptide (XIP) is trapped within a groove between the TMD and CBD2 and is predicted to clash with gating helices TMs(1/6) at the outward-facing state, thus hindering the conformational transition and promoting inactivation of the transporter. A bound SEA0400 molecule stiffens helix TM2ab and affects conformational rearrangements of TM2ab that are associated with the ion-exchange reaction, thus allosterically attenuating Ca2+-uptake activity of NCX1.3 (Dong et al. 2024). | Eukaryota |
Metazoa, Chordata | SLC8A1 of Homo sapiens |
2.A.19.3.5 | Sodium/calcium exchanger 2 (Na+/Ca2+-exchange protein 2; NCX2; SLC8A2) of 921 aas and 11 TMSs. Functional inhibition of NCX2 initially causes natriuresis, and further inhibition produces hypercalciuria, suggesting that the functional significance of NCX2 lies in Na+ and Ca+ reabsorption in the kidney (Gotoh et al. 2015). However NCX1-3 are present in the brain where they influence stroke theraputic strategies in a NCX subtype-specific fashion (Shenoda 2015). NCX1 and NCX2 play important roles in the motility of the gastric fundus, ileum and distal colon, but only NCX2 plays a role in the development of diarrhea (Nishiyama et al. 2016). | Eukaryota |
Metazoa, Chordata | SLC8A2 of Homo sapiens |
2.A.19.4.1 | Rod photoreceptor Ca2+ + K+:4 Na+ antiporter, NCKX1. NCKX1 and heterologously expressed NCKX2 operate at a 4Na+:1Ca2++1 K+ stoichiometry; both NCKX1 and NCKX2 are bidirectional transporters normally extruding Ca2+ from the cell (forward exchange), but also able to carry Ca2+ into the cell (reverse exchange) when the transmembrane Na+ gradient is reversed. Sequence changes have been observed for both NCKX1 and NCKX2 in patients with retinal diseases (Schnetkamp 2004). | Eukaryota |
Metazoa, Chordata | Ca2+ + K+:Na+ antiporter (NCKX1) of Bos taurus |
2.A.19.4.2 | The major neuronal Ca2+ + K+:4 Na+ antiporter, NCKX2. NCKX1 and NCKX2 operate with 4Na+:1Ca2++1 K+ stoichiometry; both are bidirectional transporters normally extruding Ca2+ from the cell (forward exchange), but also able to carry Ca2+ into the cell (reverse exchange) when the transmembrane Na+ gradient is reversed. Sequence changes have been observed for both NCKX1 and NCKX2 in patients with retinal diseases (Schnetkamp 2004). | Eukaryota |
Metazoa, Chordata | NCKX2 of Rattus norvegicus |
2.A.19.4.3 | The sea urchin spermatozoan flagellar K+-dependent Ca2+:Na+ antiporter SuNCKX (Ca2+ + K+:4 Na+ antiporter) | Eukaryota |
Metazoa, Echinodermata | SuNCKX of Strongylocentrotus purpuratus |
2.A.19.4.4 | K+-dependent Na+/Ca2+ antiporter, NCKX6 (Cai and Lytton, 2004). CCKX6 (NCLX) is an essential component of the mitochondrial Na+/Ca2+ exchanger (Palty et al., 2010; Drago et al., 2011). It usually mediates mitochondrial Ca2+ extrusion (De Marchi et al. 2014). However, the mitochondrial calcium uniporter channel (MCU) and mitochondrial Na+ /Ca2+ exchanger, NCLX, mediate Ca2+ entry into and release from this organelle and couple cytosolic Ca2+ and Na+ fluctuations with cellular energetics (Verkhratsky et al. 2017). Abnormal levels occur in plasma neuron-derived extracellular vesicles of early schizophrenia and other neurodevelopmental diseases (Goetzl et al. 2022). Members of this family have the Glt fold (Ferrada and Superti-Furga 2022). The mitochondrial calcium uniporter (MCU) is involved in an ischemic postconditioning effect against ischemic reperfusion brain injury in mice (Sasaki et al. 2024). Mitochondrial sodium/calcium exchanger (NCLX) regulates basal and starvation-induced autophagy through calcium signaling (Ramos et al. 2024). | Eukaryota |
Metazoa, Chordata | SLC24A6 of Homo sapiens |
2.A.19.4.5 | The K+-dependent Na+/Ca2+ exchanger, MCKX4 (has 40x higher affinity for K+ than NCKX2 due to a threonine to alanine substitution at position 551 in NCKX2 (Visser et al., 2007)). NCKX4 is highly expressed and regulates Ca2+ transport in ameloblasts during amelogenesis (the formation of tooth enamel). In fact, MCKX4 is critical for enamel maturation (Wang et al. 2014). Residues involved in Na+ binding have been identified (Altimimi et al. 2010). Inhibitors of SLC26A4 that have shown promise in the treatment of different phenotypes of diseases including asthma (Guntupalli et al. 2024). | Eukaryota |
Metazoa, Chordata | SLC24A4 of Homo sapiens |
2.A.19.4.6 | Trans-Golgi network K+-dependent Na+/Ca2+ antiporter SLC24A5 (NCKX5) (regulates melanogenesis; determines skin color variation) (Ginger et al., 2008). | Eukaryota |
Metazoa, Chordata | SLC24A5 of Homo sapiens |
2.A.19.4.7 | The endomembrane Ca2+:cation exchanger (CCX, CAX9 or CCX3); transports H+, Na+, K+ and Mn2+; expressed primarily in flowers (Morris et al., 2008). | Eukaryota |
Viridiplantae, Streptophyta | CAX9 of Arabidopsis thaliana (Q9LJI2) |
2.A.19.4.8 | K+ uptake and Na+ transporter, CCX5 (CAX11) (Zhang et al., 2011). | Eukaryota |
Viridiplantae, Streptophyta | CCX5 of Arabidopsis thaliana (O04034) |
2.A.19.4.9 | Na+/K+/Ca2+ exchanger-1 isoform 1, NCKX-1 | Eukaryota |
Metazoa, Chordata | SLC24A1 of Homo sapiens |
2.A.19.4.10 | Sodium/potassium/calcium exchanger 3 (Na+/K+/Ca2+-exchange protein 3), NCKX3, or (Solute carrier family 24 member 3), SLC24A3 (Yang et al. 2013). | Eukaryota |
Metazoa, Chordata | SLC24A3 of Homo sapiens |
2.A.19.4.11 | Sodium/potassium/calcium exchanger 2 (Na(+)/K(+)/Ca(2+)-exchange protein 2) (Retinal cone Na-Ca+K exchanger) (Solute carrier family 24 member 2) | Eukaryota |
Metazoa, Chordata | SLC24A2 of Homo sapiens |
2.A.19.4.12 | Putative Ca2+:cation exchanger of 1524 aas and an apparent duplication with 27 putative | Eukaryota |
Metazoa, Chordata | Putative Ca2+: cation exchanger of Branchiostoma floridae |
2.A.19.4.13 | Uncharacterized protein of 623 aas. | Eukaryota |
UP of Aureococcus anophagefferens (Harmful bloom alga) | |
2.A.19.4.14 | Ca2+:Na+ exchanger, NCX-9 of 651 aas and 14 TMSs. Plays a role in developmental cell patterning and Ca2+ exchange in mitochondrial (Sharma et al. 2017). | Eukaryota |
Metazoa, Nematoda | NCX-9 of Caenorhabditis elegans |
2.A.19.4.15 | Putative sodium:calcium symporter of 377 aas and 10 TMSs. | Viruses |
Caudovirales | Na+:Ca2+ symporter of Pseudoalteromonas phage J2-1 |
2.A.19.4.16 | Uncharacterized protein of 575 aas and 10 TMSs in a 4 + 6 TMS arrangement. | Eukaryota |
Perkinsozoa | UP of Entamoeba histolytica |
2.A.19.5.1 | Putative Ca2+:H+ or Ca2+:Na+ antiporter with two 5 TMS internal repeats (Sääf et al. 2001). | Bacteria |
Pseudomonadota | ChaB (YrbG) of E. coli |
2.A.19.5.2 | Cation (Ca2+/Na+):proton antiporter, ChaA or CaxA (confers both Na+ and Ca2+ resistance) (Wei et al., 2007) | Bacteria |
Pseudomonadota | ChaA of Alkalimonas amylolytica (Q0ZAI3) |
2.A.19.5.3 | Na+:Ca2+ exchanger, NCX_Mj (3-d structure known at 1.9 Å resolution; PDB# 3V5U (Liao et al., 2012). Contains 10 TMSs with two 5 TMS repeats. Four ion binding sites near the center of the protein are present, one specific for Ca2+ and three probably for Na+. Two passageways allow for Na+ and Ca2+ access from the external side. However see a more recent analysis reported for 2.A.19.8.2 (Nishizawa et al. 2013). Transport of both Na+ and Ca2+ requires protonation of D240, but this side chain does not coordinate either ion, implying that the ion exchange stoichiometry is 3:1 and that translocation of Na+ across the membrane is electrogenic although transport of Ca2+ is not (Marinelli et al. 2014). This system has been reviewed and considered to be a model protein for the entire family (Khananshvili 2021). | Archaea |
Euryarchaeota | NCX_Mj of Methanococcus (Methanocaldococcus) jannaschii (Q57556) |
2.A.19.5.4 | Na+/Ca2+ exchanger. Transport is electrogenic with a likely stoichiometry of 3 or more Na+ for each Ca2+ but K+-independent (Besserer et al. 2012). | Archaea |
Euryarchaeota | MaX1 of Methanosarcina acetivorans |
2.A.19.6.1 | Vacuolar electrogenic Mg2+, Zn2+, Fe2+, and possibly Cd2+:H+ antiporter, MHX (found in the vascular cylinder; may control the partitioning of Mg2+ and Zn2+ between plant organs). MHX porters are found only in plants and probably have 9 TMSs. Their properties have been reviewed (Gaash et al. 2013). | Eukaryota |
Viridiplantae, Streptophyta | MHX of Arabidopsis thaliana (O22252) |
2.A.19.7.1 | Low affinity vacuolar monovalent cation (Na+ (Km=20 mM) or K+(Km=80 mM)):H+ antiporter, Vnx1. (Ca2+ is not transported; plays roles in ion and pH homeostasis) (Cagnac et al., 2007) | Eukaryota |
Fungi, Ascomycota | Vnx1 of Saccharomyces cerevisiae (P42839) |
2.A.19.7.2 | Uncharacterized protein of 739 aas. | Eukaryota |
Metazoa, Chordata | UP of Ornithorhynchus anatinus (Duckbill platypus) |
2.A.19.8.1 | Calcium:proton exchanger, CAX(CK31). The function was demonstrated by purification and reconstitution in liposomes (Ridilla et al. 2012). The protein forms dimers in the membrane but can be purified as a monomer. The dimer interface seems to involve TMSs 2 and 6 (Ridilla et al. 2012). | Bacteria |
Pseudomonadota | CAX(CD31) of Caulobacter sp. strain K31 |
2.A.19.8.2 | Ca2+:H+ antiporter of 405 aas, CAX_Af. The inward facing 3-d structure has been solved to 2.3 Å resolution (Nishizawa et al. 2013). The authors compare this structure to the outward facing 1.9 Å structure of NCX_Mj (TC# 2.A.19.5.3) and suggest that Ca2+ or H+ binds to the cation-binding site mutually exclusively. The first and sixth TMSs alternately create hydrophilic cavities on the intra- and extracellluar sides of the membrane. The inward and outward-facing transitions are triggered by ion binding (Nishizawa et al. 2013). | Archaea |
Euryarchaeota | Ca2+:H+ antiporter CAX_Af of Archaeoglobus fulgidus |
2.A.19.9.1 | Mg2+ transporter (Mg2+-specific channel-like exchanger) of 550 aas (Preston and Kung 1994; Haynes et al. 2002). Has 10 putative TMSs in a 5 + 5 TMS arrangement and exhibits properties of a channel (Haynes et al. 2002). The mutant form is called 'eccentric' and exhibits backwards swimming behavior (Preston and Kung 1994). | Eukaryota |
Ciliophora | Ca2+-dependent Mg2+ transporter of Paramecium tetraurelia |
2.A.19.9.2 | Probable Mg2+-specific channel-like exchanger of 625 aas. | Eukaryota |
Ciliophora | Probable Mg2+-specific channel-like exchanger of Tetrahymena thermophila |
2.A.19.10.1 | Putative CaCA family member of 368 aas and 10 TMSs | Eukaryota |
Evosea | UP of Dictyostelium discoideum |
2.A.19.10.2 | Uncharacterized protein of 518 aas and 10 TMSs | Eukaryota |
Metazoa, Placozoa | UP of Trichoplax adhaerens (Trichoplax reptans) |