2.A.2 The Glycoside-Pentoside-Hexuronide (GPH):Cation Symporter Family

GPH:cation symporters catalyze uptake of sugars (mostly, but not exclusively, glycosides) in symport with a monovalent cation (H+ or Na+). Mutants of two groups of these symporters (the melibiose permeases of enteric bacteria and the lactose permease of Streptococcus thermophilus) have been isolated and in which altered cation specificity is observed or in which sugar transport is uncoupled from cation symport (i.e., uniport is catalyzed). The various members of the family can use Na+, H+ or Li, Na+ or Li+, H+ or Li+, or only H+ as the symported cation. Most functionally characterized and sequenced members of the family are from bacteria except the distantly related sucrose:H+ symporters of plants and a yeast maltose/sucrose:H+ symporter of S. pombe. This yeast protein is about 24% identical to the plant sucrose:H+ symporters and is more distantly related to the bacterial members of the GPH family (Reinders and Ward, 2001). Homologues are found in archaea and all eukaryotic kingdoms.

Proteins of the GHP family are generally about 500 amino acids in length, although the Gram-positive bacterial lactose permeases are larger, due to a C-terminal hydrophilic domain that is involved in regulation by the phosphotransferase system (TC #4.A.1). All of these proteins possess twelve putative transmembrane α-helical spanners. Limited sequence similarity of some of these proteins with members of the major facilitator superfamily (MFS, TC #2.A.1) has been observed. PSI-BLAST results substantiate the conclusion that the GPH family is a member of the MFS. One member of the GPH family, LacS of Streptococcus thermophilus, appears to be a cooperative dimer with one sugar translocation pathway per monomer (Veenhoff et al., 2001).

The generalized transport reaction catalyzed by the GPH:cation symporter family is:

Sugar (out) + [H+ or Na+] (out) → Sugar (in) + [H+ or Na+] (in).



This family belongs to the MFS Superfamily.

 

References:

Andersen, J.M., R. Barrangou, M. Abou Hachem, S. Lahtinen, Y.J. Goh, B. Svensson, and T.R. Klaenhammer. (2011). Transcriptional and functional analysis of galactooligosaccharide uptake by lacS in Lactobacillus acidophilus. Proc. Natl. Acad. Sci. USA 108: 17785-17790.

Bartölke, R., J.J. Heinisch, H. Wieczorek, and O. Vitavska. (2014). Proton-associated sucrose transport of mammalian solute carrier family 45: an analysis in Saccharomyces cerevisiae. Biochem. J. 464: 193-201.

Bassik, M.C. and M. Kampmann. (2011). Knocking out the door to tunicamycin entry. Proc. Natl. Acad. Sci. USA 108: 11731-11732.

Carpaneto, A., D. Geiger, E. Bamberg, N. Sauer, J. Fromm, and R. Hedrich. (2005). Phloem-localized, proton-coupled sucrose carrier ZmSUT1 mediates sucrose efflux under the control of the sucrose gradient and the proton motive force. J. Biol. Chem. 280: 21437-21443.

Carpaneto, A., H. Koepsell, E. Bamberg, R. Hedrich, and D. Geiger. (2010). Sucrose- and H-dependent charge movements associated with the gating of sucrose transporter ZmSUT1. PLoS One 5: e12605.

Chaillou, S., P.W. Postma, and P.H. Pouwels. (1998). Functional expression in Lactobacillus plantarum of xylP encoding the isoprimeverose transporter of Lactobacillus pentosus. J. Bacteriol. 180: 4011-4014.

Deol KK., Mukherjee S., Gao F., Brule-Babel A., Stasolla C. and Ayele BT. (2013). Identification and characterization of the three homeologues of a new sucrose transporter in hexaploid wheat (Triticum aestivum L.). BMC Plant Biol. 13:181.

Du, J. and D.E. Fisher. (2002). Identification of Aim-1 as the underwhite mouse mutant and its transcriptional regulation by MITF. J. Biol. Chem. 277: 402-406.

Ethayathulla, A.S., M.S. Yousef, A. Amin, G. Leblanc, H.R. Kaback, and L. Guan. (2014). Structure-based mechanism for Na+/melibiose symport by MelB. Nat Commun 5: 3009.

Granell, M., X. León, G. Leblanc, E. Padrós, and V.A. Lórenz-Fonfría. (2010). Structural insights into the activation mechanism of melibiose permease by sodium binding. Proc. Natl. Acad. Sci. USA 107: 22078-22083.

Grossiord, B.P., E.J. Luesink, E.E. Vaughan, A. Arnaud, and W.M. de Vos. (2003). Characterization, expression, and mutation of the Lactococcus lactis galPMKTE genes, involved in galactose utilization via the Leloir pathway. J. Bacteriol. 185: 870-878.

Hariharan, P. and L. Guan. (2014). Insights into the inhibitory mechanisms of the regulatory protein IIA(Glc) on melibiose permease activity. J. Biol. Chem. 289: 33012-33019.

Heuberger, E.H., E. Smits, and B. Poolman. (2001). Xyloside transport by XylP, a member of the galactoside-pentoside-hexuronide family. J. Biol. Chem. 276: 34465-34472.

Hugouvieux-Cotte-Pattat, N. and S. Reverchon. (2001). Two transporters, TogT and TogMNAB, are responsible for oligogalacturonide uptake in Erwinia chrysanthemi 3937. Molec. Microbiol. 41: 1125-1132.

Inagaki, K., T. Suzuki, S. Ito, N. Suzuki, K. Adachi, T. Okuyama, Y. Nakata, H. Shimizu, H. Matsuura, T. Oono, H. Iwamatsu, M. Kono, and Y. Tomita. (2006). Oculocutaneous albinism type 4: six novel mutations in the membrane-associated transporter protein gene and their phenotypes. Pigment Cell Res 19: 451-453.

Kamaraj, B. and R. Purohit. (2016). Mutational Analysis on Membrane Associated Transporter Protein (MATP) and Their Structural Consequences in Oculocutaeous Albinism Type 4 (OCA4) - A Molecular Dynamics Approach. J. Cell. Biochem. [Epub: Ahead of Print]

Laikova, O.N., A.A. Mironov, and M.S. Gelfand. (2001). Computational analysis of the transcriptional regulation of pentose utilization systems in the gamma subdivision of Proteobacteria. FEMS Microbiol. Lett. 205: 315-322.

Liang, W.-J., K.J. Wilson, H. Xie, J. Knol, S. Suzuki, N.G. Rutherford, P.J.F. Henderson, and R.A. Jefferson. (2005). The gusBC genes of Escherichia coli encode a glucuronide transport system. J. Bacteriol. 187: 2377-2385.

Lohmiller, S., K. Hantke, S.I. Patzer, and V. Braun. (2008). TonB-dependent maltose transport by Caulobacter crescentus. Microbiology 154: 1748-1754.

Meyer S., M. Melzer, E. Truernit, C. Hümmer, R. Besenbeck, R. Stadler, N. Sauer. (2000). AtSUC3, a gene encoding a new Arabidopsis sucrose transporter, is expressed in cells adjacent to the vascular tissue and in a carpel cell layer. Plant J. 24: 869-882

Meyer, H., O. Vitavska, and H. Wieczorek. (2011). Identification of an animal sucrose transporter. J Cell Sci 124: 1984-1991.

Moraes, T.F. and R.A. Reithmeier. (2012). Membrane transport metabolons. Biochim. Biophys. Acta. 1818: 2687-2706.

Naderi, S. and M.H. Saier, Jr. (1996). Plant sucrose:H+ symporters are homologous to the melibiose permease of Escherichia coli. Molec. Microbiol. 22: 389-391.

Osanai-Futahashi M., Tatematsu K., Yamamoto K., Narukawa J., Uchino K., Kayukawa T., Shinoda T., Banno Y., Tamura T. and Sezutsu H. (2012). Identification of the Bombyx red egg gene reveals involvement of a novel transporter family gene in late steps of the insect ommochrome biosynthesis pathway. J Biol Chem. 287(21):17706-14.

Pommerrenig B., Popko J., Heilmann M., Schulmeister S., Dietel K., Schmitt B., Stadler R., Feussner I. and Sauer N. (2013). SUCROSE TRANSPORTER 5 supplies Arabidopsis embryos with biotin and affects triacylglycerol accumulation. Plant J. 73(3):392-404.

Poolman, B., J. Knol, C. van der Does, P.J.F. Henderson, W.-J. Liang, G. Leblanc, T. Pourcher, and I. Mus-Veteau. (1996). Cation and sugar selectivity determinants in a novel family of transport proteins. Molec. Microbiol. 19: 911-922.

Quek, D.Q., L.N. Nguyen, H. Fan, and D.L. Silver. (2016). Structural insights into the transport mechanism of the human sodium-dependent lysophosphatidylcholine transporter Mfsd2a. J. Biol. Chem. [Epub: Ahead of Print]

Reiling, J.H., C.B. Clish, J.E. Carette, M. Varadarajan, T.R. Brummelkamp, and D.M. Sabatini. (2011). A haploid genetic screen identifies the major facilitator domain containing 2A (MFSD2A) transporter as a key mediator in the response to tunicamycin. Proc. Natl. Acad. Sci. USA 108: 11756-11765.

Reinders, A. and J.M. Ward. (2001). Functional characteristic of the α-glucoside transporter Sut1p from Schizosaccharomyces pombe, the first fungal homologue of plant sucrose transporters. Molec. Microbiol. 39: 445-454.

Reizer, J., A. Reizer, and M.H. Saier, Jr. (1994). A functional superfamily of sodium/solute symporters. Biochim. Biophys. Acta 1197: 133-166.

Rodionov, D.A., C. Yang, X. Li, I.A. Rodionova, Y. Wang, A.Y. Obraztsova, O.P. Zagnitko, R. Overbeek, M.F. Romine, S. Reed, J.K. Fredrickson, K.H. Nealson, and A.L. Osterman. (2010). Genomic encyclopedia of sugar utilization pathways in the Shewanella genus. BMC Genomics 11: 494.

Rodionov, D.A., M.S. Gelfand, and N. Hugouvieux-Cotte-Pattat. (2004). Comparative genomics of the KdgR regulon in Erwinia chrysanthemi 3937 and other γ-proteobacteria. Microbiology 150: 3571-3590.

Rodríguez-Díaz, J., A. Rubio-del-Campo, and M.J. Yebra. (2012). Lactobacillus casei ferments the N-Acetylglucosamine moiety of fucosyl-α-1,3-N-acetylglucosamine and excretes L-fucose. Appl. Environ. Microbiol. 78: 4613-4619.

Saier, M.H., Jr. (1989). Protein phosphorylation and allosteric control of inducer exclusion and catabolite repression by the bacterial phosphoenolpyruvate: sugar phosphotransferase system. Microbiol Rev 53: 109-120.

Schulz, A., D. Beyhl, I. Marten, A. Wormit, E. Neuhaus, G. Poschet, M. Büttner, S. Schneider, N. Sauer, and R. Hedrich. (2011). Proton-driven sucrose symport and antiport are provided by the vacuolar transporters SUC4 and TMT1/2. Plant J. 68: 129-136.

Shimokawa, N., J. Okada, K. Haglund, I. Dikic, N. Koibuchi, and M. Miura. (2002). Past-A, a novel proton-associated sugar transporter, regulates glucose homeostasis in the brain. J. Neurosci. 22: 9160-9165.

Stadler R., E. Truernit, M. Gahrtz, N. Sauer. (1999). The AtSUC1 sucrose carrier may represent the osmotic driving force for anther dehiscence and pollen tube growth in Arabidopsis. Plant J. 19: 269-278.

Sun, Y. and J.M. Ward. (2012). Arg188 in rice sucrose transporter OsSUT1 is crucial for substrate transport. BMC Biochem 13: 26.

Tóth, L., B. Fábos, K. Farkas, A. Sulák, K. Tripolszki, M. Széll, and N. Nagy. (2017). Identification of two novel mutations in the SLC45A2 gene in a Hungarian pedigree affected by unusual OCA type 4. BMC Med Genet 18: 27.

Veenhoff, L.M., Heuberger, E.H.M.L., and B. Poolman. (2001). The lactose transport protein is a cooperative dimer with two sugar translocation pathways. EMBO J. 20: 3056-3062.

Wang, L.Y., V.M. Ravi, G. Leblanc, E. Padrós, J. Cladera, and A. Perálvarez-Marín. (2016). Helical unwinding and side-chain unlocking unravel the outward open conformation of the melibiose transporter. Sci Rep 6: 33776.

Wijesena, H.R. and S.M. Schmutz. (2015). A Missense Mutation in SLC45A2 Is Associated with Albinism in Several Small Long Haired Dog Breeds. J Hered 106: 285-288.

Yousef, M.S. and L. Guan. (2009). A 3D structure model of the melibiose permease of Escherichia coli represents a distinctive fold for Na+ symporters. Proc. Natl. Acad. Sci. USA 106: 15291-15296.

Zhang, C. and R. Turgeon. (2009). Downregulating the sucrose transporter VpSUT1 in Verbascum phoeniceum does not inhibit phloem loading. Proc. Natl. Acad. Sci. USA 106: 18849-18854.

Examples:

TC#NameOrganismal TypeExample
2.A.2.1.1

Melibiose permease. Catalyzes the coupled stoichiometric symport of a galactoside with a cation (either Na+, Li+, or H+). Based on LacY, a 3-d model has been derived (Yousef and Guan, 2009). Asp55 and Asp59 are essential for Na+ binding. Asp124 may play a critical role by allowing Na+-induced conformational changes and sugar binding. Asp19 may facilitate melibiose binding (Granell et al., 2010).  The alternate access mechanism fits better into a flexible gating mechanism rather than the archetypical helical rigid- body rocker-switch mechanism (Wang et al. 2016).  Crystal structures of Salmonella typhimurium MelB in two conformations, representing an outward partially occluded and an outward inactive state (Ethayathulla et al. 2014). MelB adopts a typical MFS fold and contains a previously unidentified cation-binding motif. Three conserved acidic residues form a pyramidal-shaped cation-binding site for Na+, Li+ or H+, which is in close proximity to the sugar-binding site. Both cosubstrate-binding sites are mainly contributed by the residues from the amino-terminal domain (Ethayathulla et al. 2014). The Glucose Enzyme IIA protein of the PTS binds MelB either in the absence or presence of a galactoside, and binding decreases the affinity for melibiose, giving rise to inducer exclusion (Saier 1989; Hariharan and Guan 2014).

Gram-negative bacteria

MelB of E. coli (A7ZUZ0)

 
2.A.2.1.2

Probable fucosyl-α-1,6-N-acetylglucosamine uptake porter, AlfD (next to and in an operon with a fucosidase (AlfA) specific for this disaccharide which is present in mammalian glycoproteins, glycolipids and milk (Rodríguez-Díaz et al. 2012).

Firmicutes

AlfD of Lactobacillus casei

 
2.A.2.1.3

Uncharacterized protein, probably a sugar:H+ symporter of 474 aas and 12 TMSs, YjmB,  The gene was from a marine sediment metagenome.

YjmB of Lokiarchaeum sp. GC14_75

 
Examples:

TC#NameOrganismal TypeExample
2.A.2.2.1

Lactose permease, LacS. Mediates uptake of β-galactooligosaccharides, lactitol, and a broad range of prebiotic β-galactosides that selectively stimulate beneficial gut microbiota (Andersen et al., 2011). 

Gram-positive bacteria

LacS of Streptococcus thermophilus

 
2.A.2.2.2Raffinose permease Gram-positive bacteria RafP of Pediococcus pentosaceus
 
2.A.2.2.3

Galactose permease of 462 aas and 12 TMSs.  Transports galactose (Grossiord et al. 2003).

Gram-positive bacteria

GalP of Lactococcus lactis

 
Examples:

TC#NameOrganismal TypeExample
2.A.2.3.1

Glucuronide permease, UidB, GusB, UidP (Liang et al., 2005; Moraes and Reithmeier 2012)

Gram-negative bacteria

GusB of E. coli

 
2.A.2.3.10Transmembrane protein 180AnimalsTMEM180 of Homo sapiens
 
2.A.2.3.11

Putative transporter

Euglenozoa

Putative transporter of Trypanosoma cruzi

 
2.A.2.3.12

Putative sugar transporter

Bacteria

TT_P0219 pf Thermus thermophilus

 
2.A.2.3.13

Probable sugar transporting MFS-2 symporter of 444 aas and 12 TMSs.

MFS carrier of Candidatus Thorarchaeota archaeon

 
2.A.2.3.2Pentoside permease Gram-positive bacteria XynC (YnaJ) of Bacillus subtilis
 
2.A.2.3.3

Isoprimeverose (α-D xylopyranosyl-(1,6)-D-glucopyranose) permease [xylose is not a substrate] (Heuberger et al., 2001)

Gram-positive bacteria

XylP of Lactobacillus pentosus

 
2.A.2.3.4Probable α-xyloside uptake permease, YicJ (Laikova et al., 2001)BacteriaYicJ of E. coli (P31435)
 
2.A.2.3.5Probable β-xyloside uptake permease, YagG (Laikova et al., 2001)BacteriaYagG of E. coli (P75683)
 
2.A.2.3.6

The putative cellobiose porter, BglT (Rodionov et al. 2010)

Proteobacteria

BglT of Shewanella amazonensis (A1S5F2)

 
2.A.2.3.7

The putative arabinoside porter, AraT (Rodionov et al., 2010)

Proteobacteria

AraT of Shewanella sp. MR-4 (Q0HIQ0)

 
2.A.2.3.8

Major Facilitator Superfamily Domain containing 2A, MFSD2A (543aas, 12 TMSs). Plays a role in thermogenesis via β-adrenergic signaling. Takes up Tunicamycin (TM), a mixture of related species of nucleotide sugar analogs fatty-acylated with alkyl chains of varying lengths and degrees of unsaturation, produced by several Streptomyces species (Bassik and Kampmann, 2011; Reiling et al., 2011).  It is a sodium-dependent lysophosphatidylcholine (LPC) transporter expressed at the blood-brain barrier endothelium. It is the primary route for import of docosahexaenoic acid and other long-chain fatty acids into foetal and adult brain, and is essential for mouse and human brain growth and function (Quek et al. 2016). In addition to a conserved sodium-binding site, three structural features were identified: A phosphate headgroup binding site, a hydrophobic cleft to accommodate a hydrophobic hydrocarbon tail, and three sets of ionic locks that stabilize the outward-open conformation. Ligand docking studies and biochemical assays identified Lys436 as a key residue for transport. It forms a salt bridge with the negative charge on the phosphate headgroup. Mfsd2a transports structurally related acylcarnitines but not a lysolipid without a negative charge, demonstrating the necessity of a negative charged headgroup interaction with Lys436 for transport. These findings support a novel transport mechanism by which LPCs are flipped within the transporter cavity by pivoting about Lys436 leading to net transport from the outer to the inner leaflet of the plasma membrane (Quek et al. 2016).

Animals

MFSD2A of Homo sapiens (Q8NA29)

 
2.A.2.3.9

Inner membrane symporter YihP

Bacteria

YihP of E. coli

 
Examples:

TC#NameOrganismal TypeExample
2.A.2.4.1

Sucrose:H+ symporter, Suc1 (provides osmotic driving force for anther dehiscence, pollen germination and pollen tube growth; also transports other glucosides such as maltose and phenylglucosides. Km (sucrose)= 0.5 mM. (Stadler et al., 1999)).  In wheat (Triticum aesticum), there are at least three isoforms designated Sut2A, Sut2B and Sut2D (Deol et al. 2013).

Plants

Suc1 of Arabidopsis thaliana

 
2.A.2.4.10

Proton:glucose symporter A; proton-associated sugar transporter A  (PAST-A) (present in brain and deleted in neuroblastoma 5 (DNb-5).  Solute carrier family 45 member 1, SLC45A1 (Bartölke et al. 2014).

Animals

SLC45A1 of Homo sapiens

 
2.A.2.4.11Sucrose transport protein SUT5 (Sucrose permease 5) (Sucrose transporter 5) (OsSUT5) (Sucrose-proton symporter 5)PlantsSUT5 of Oryza sativa subsp. japonica
 
2.A.2.4.12

Sucrose:H+ symporter, SUC5.  Also transports biotin and possibly maltose (Pommerrenig et al. 2012).

Plants

SUC5 of Arabidopsis thaliana

 
2.A.2.4.13

Scratch, orthologue 1, SCRT; SLC45A2; transports sucrose into pigment-containing vesicles or granules.  Mutations give rise to oculocutaneous albinism (Meyer et al. 2011).

Animals

SCRT of Drosophila melanogaster

 
2.A.2.4.14

Melanocyte-specific antigen or melanoma antigen, MatP, Slc45a2, Aim-1, AIM1, at the mouse underwhite locus.  Regulated by a melanocyte-specific transcription factor essential for pigmentation, MITF (Du and Fisher 2002). Mutations in MatP in humans cause oculocutaneous albinism type IV (OCA4), an autosomal recessive inherited disorder which is characterized by reduced biosynthesis of melanin pigmentation in skin, hair and eyes. The MATP protein consists of 530 amino acids which contains 12 TMSs (Kamaraj and Purohit 2016).  The D93N mutation causes oculocutaneous albinism 4 (OCA4), and the L374F mutatioin correlates with light pigmentation in European populations. Corresponding mutations were produced in the related and well-characterized sucrose transporter from rice, OsSUT1, and transport activity was measured by heterologous expression in Xenopus laevis oocytes and 14C-sucrose uptake in yeast. The D93N mutant had completly lost transport activity while the L374F mutant showed a 90% decrease in transport activity, although the substrate affinity was unaffected (Kamaraj and Purohit 2016).  Mutations in MATP protein showed loss of stability and became more flexible, which alter its structural conformation and function (Kamaraj and Purohit 2016).

Aim1 of Mus musculus

 
2.A.2.4.2

Phloem-localized sucrose:H+ symporter, Sut1 (mediates sucrose uptake or efflux dependent on the sucrose gradient and the pmf; Carpaneto et al., 2005). Sut1 is a sucrose protein symporter. Protons can move in the absence of sucrose (Carpaneto et al., 2010), but upon addition of sucrose, it becomes a symporter.  Arg-188 in the rice orthologue and homologues are essential (Sun and Ward 2012).

Plants

Sut1 of Zea mays (BAA83501)

 
2.A.2.4.3

Sucrose:H+ symporter, Suc3 or Sut3 of 464 aas. Expressed in cells adjacent to the vascular tissue and in a carpel cell layer). Km (sucrose)= 1.9 mM; maltose is a competitor (Meyer et al., 2000).

Plants

Suc3 of Arabidopsis thaliana
(O80605)

 
2.A.2.4.4The brain proton:associated sugar (glucose) transporter, PAST-A (Shimokawa et al., 2002)Animals PAST-A of Rattus norvegicus (Q8K4S3)
 
2.A.2.4.5

The proton:sucrose uptake symporter, Sut1 (Zhang & Turgeon et al., 2009).

Plants

Sut1 of Verbascum phoeniceum (D1GC38)

 
2.A.2.4.6

Vacuolar sucrose;H+ symporter Suc4, Catalyzes sucrose export from vacuoles (Schulz et al., 2011)

Plants

Suc4 of Arabidopsis thaliana (Q9FE59)

 
2.A.2.4.7

Solute carrier family 45, member 4, SLC45A4.  Transports sucrose by a proton symport mechanism.  Found ubiquitously throughout the tissues of the body (Bartölke et al. 2014).

Animals

SLC45A4 of Homo sapiens

 
2.A.2.4.8

solute carrier family 45, member 3, Slc45A3.  Sucrose:proton symporter associated with prostate cancer and myelination (Bartölke et al. 2014).

Animals

SLC45A3 of Homo sapiens

 
2.A.2.4.9

Solute carrier family 45, member 2, Slc45A2, also called melanocyte-restricted antigen or melanoma antigen, PatP, Aim-1 or Aim1.  Transports sucrose with protons, possibly into vesicular structures that contain melanin.  Found in skin and hair; involved in pigmentation (Bartölke et al. 2014).  Defects give rise to oculocutaneous albinism (Meyer et al. 2011). One such mutation in dogs, G493D in TMS 11, gives rise to albinisms (Wijesena and Schmutz 2015). OCA type IV (OCA4, OMIM 606574) develops due to homozygous or compound heterozygous mutations in the solute carrier family 45, member 2 (SLC45A2) gene, and many mutations in this human gene have been identified (Inagaki et al. 2006; Tóth et al. 2017).

Animals

SLC45A2 of Homo sapiens

 
Examples:

TC#NameOrganismal TypeExample
2.A.2.5.1

Saturated and unsaturated oligogalacturonide transporter, TogT (transports di- to tetrasaccharide pectin degradation products which consist of D-galacuronate, sometimes with 4-deoxy-L-threo-5- hexosulose uronate at the reducing position)

Bacteria TogT of Erwinia chrysanthemi 3937
 
2.A.2.5.2

The putative rhamnogalacturonide porter, RhiT (Rodionov et al. 2004).

Enterobacteria

RhiT of Erwinia carotovora subsp. atroseptica (Q6D188)

 
Examples:

TC#NameOrganismal TypeExample
2.A.2.6.1

Maltose/sucrose H+ : symporter, Sut1 (maltose, Km = 6 %u03BCM; sucrose, Km = 36 %u03BCM)

Yeast

Sut1 of Schizosaccharomyces pombe

 
2.A.2.6.2

The maltose/maltooligosaccharide transporter, MalI (541 aas) (Lohmiller et al., 2008).

Bacteria

MalI of Caulobacter crescentus (Q9A612)

 
2.A.2.6.3

The putative maltose porter, MalT (Rodionov et al., 2010)

Proteobacteria

MalT of Shewanella oneidensis (Q8EEC4)

 
Examples:

TC#NameOrganismal TypeExample
2.A.2.7.1

The insect Bm-re (Bombyx mori red eye) protein; mutants lose ommochromes as well as pigmentation of eggs, eyes, and bodies. May function in pigment transport (Osanai-Futahashi et al., 2012).

Insects

Bm-re of Bombyx mori (I0IYT1)

 
2.A.2.7.2

Bm-re homologue of Tribolium castaneum (Osanai-Futahashi et al., 2012).

Insects

Bm-re homologue of Tribolium castaneum (D6W6W0)