TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameDomainKingdom/PhylumProtein(s)
*2.A.123.1.1









Alfalfa Nodulin MtN3

Eukaryota
Viridiplantae
MtN3 of Medicago truncatula (P93332)
*2.A.123.1.2









Sweet family member of 305 aas and 7 TMSs.  Mediates both low-affinity uptake and efflux of sugars across the membrane. (Wu et al., 2008)

Eukaryota
Viridiplantae
Sweet of Citrus clementina
*2.A.123.1.3









Senescence-associated protein 29, SAG29 (SWEET15)

Eukaryota
Viridiplantae
SAG29 of Arabidopsis thaliana (Q9FY94)
*2.A.123.1.4









Stromal cell protein (SCP) homologue, HsSWEET1 or RAG1AP1. Transports glucose and galactose bidirectionally. Present in the ER, Golgi and plasma membrane (Chen et al., 2010).

Eukaryota
Metazoa
SLC50A1 of Homo sapiens
*2.A.123.1.5









Ruptured pollen Grain-1, Sweet8 or Nodulin MtN3 family protein (essential for pollen viability). (Guan et al., 2008; Chen et al. 2010).

Eukaryota
Viridiplantae
RPGI of Arabidoposis thaliana (Q8LFH5)
*2.A.123.1.6









Host disease susceptible protein, Xa13 or Os8N3, for bacterial blight (Yang et al., 2006; Chu et al., 2006). Bidirectional sugar transporter, Sweet 11 (Chen et al., 2010)

Eukaryota
Viridiplantae
Oryza sativa (Q6YZF3)
*2.A.123.1.7









Nec1; predominantly expressed in nectaries; involved in sugar metabolism and nectar secretion (Ge et al., 2000)

Eukaryota
Viridiplantae
Nec1 of Petunia hybrida (Q9FPN0)
*2.A.123.1.8









Rga (Recombination-activating gene 1) (Hamada et al., 2005)

Eukaryota
Metazoa
Rga of Mus musculus (Q9CXK4)
*2.A.123.1.9









Sweet1: bidirectional low affinity glucose uniporter, Km = ~9 mM (Does not transport mannose, fructose or galactose) (Chen et al. 2010). The structure is know, and three regions, each containing several well conserved essential residues, comprise the substrate-binding pocket, the extrafacial gate, and the intrafacial gate (Xuan et al. 2013; Tao et al. 2015).  The orthologous SWEET1 in Camellia sinensis (tea) transports glucose, glucose analogues, and other hexoses (Wang et al. 2018).

 

 

 

Eukaryota
Viridiplantae
Sweet1 of Arabidopsis thalinana (Q8L9J7)
*2.A.123.1.10









Golgi/E.R. Sweet1 glucose/galactose facilitator (Km ≥ 50mM) (Chen et al. 2010)

Eukaryota
Metazoa
Sweet1 of Caenorhabditis elegans (O45102)
*2.A.123.1.11









The sea squirt sugar transporter, Rga or Sweet1; required for normal development (Hamada et al., 2007; Chen et al., 2010).

Eukaryota
Metazoa
Rga of Ciona intestinalis (F6U696)
*2.A.123.1.12









Sugar transporter SWEET1 (Protein saliva)
Eukaryota
Metazoa
Slv of Drosophila melanogaster
*2.A.123.1.13









Bidirectional sugar (sucrose) transporter SWEET11 (AtSWEET11).  Oligomerization, probably to the dimeric form, has been demonstrated (Xuan et al. 2013). Important for phloem loading.

Eukaryota
Viridiplantae
SWEET11 of Arabidopsis thaliana
*2.A.123.1.14









Sugar transporter SWEET1
Eukaryota
Dictyosteliida
slc50a1 of Dictyostelium discoideum
*2.A.123.1.15









SWEET homologue of 375 aas and 7 TMSs in a 3 + 4 arrangement.

Eukaryota
Bacillariophyta
SWEET homologue of Phaeodactylum tricornutum
*2.A.123.1.16









Uncharacterized protein of 262 aas and 7 TMSs

Eukaryota
Bangiophyceae
UP of Galdieria sulphuraria (Red alga)
*2.A.123.1.17









MtN3-like protein of 686 aas and 7-8 TMSs

Eukaryota
Apicomplexa
MtN3-like protein of Plasmodium falciparum
*2.A.123.1.18









SWEET2b sugar transporter. Sequesters sugars in root vacuoles.  The 3-d structure is known. The subunit consists of two asymetic triple helix bundles (TMSs 1-3 and 5-7) connected by TMS4. SWEET2b is in an apparent inward (cytosolic) open state forming homomeric trimers. TMS4 tightly interacts with the first triple-helix bundle within a protomer and mediates key contacts among protomers (Tao et al. 2015).

Eukaryota
Viridiplantae
SWEET2b of Oryza sativa
*2.A.123.1.19









Sweet1 (SLC50A1).  99.6% identical to the goat (Capra hircus) mammary gland epithelial homologue which has been characterized (Zhu et al. 2015).

Sweet1 of Ovis aries (sheep)
*2.A.123.1.20









Uncharacterized protein of 197 aas and 7 TMSs

Bacteria
Actinobacteria
UP of Acidimicrobium sp. BACL27
*2.A.123.1.21









Uncharacterized duplicated protein of 709 aas and 15 TMSs in a 7 + 7 + 1 arrangement. The protein contains two 7 TMS Sweet domains followed by an Atrophin-1 domain. There is no close homologue in the NCBI database, suggesting that it could be a result of a sequencing artifact.

Eukaryota
Viridiplantae
UP of Ananas comosus
*2.A.123.1.22









Uncharacterized protein of 1089 aas and 28 TMSs in a 7 + 7 + 7 + 7 arrangement.

Eukaryota
Oomycetes
UP of Phytophthora ramorum (Sudden oak death agent)
*2.A.123.1.23









Vacuolar texose transporter of 230 aas and 7 TMSs, Sweet16 (Eom et al. 2015). It plays an iimportant role in cold tolerance (Wang et al. 2018).

Eukaryota
Viridiplantae
Sweet16 of Arabidopsis thaliana (Mouse-ear cress)
*2.A.123.1.24









Sweet9 of 258 aas and 7 TMSs.  Important for nectar secretion (Eom et al. 2015).

Eukaryota
Viridiplantae
Sweet9 of Arabidopsis thaliana (Mouse-ear cress)
*2.A.123.1.25









Sweet family member of 89 aas and 3 TMSs.  Associated with a trehalose phosphatase, possibly suggesting al role in trehalose transport.

Archaea
Euryarchaeota
Semi-sweet of Methanobacterium lacus
*2.A.123.1.26









Sweet13 of 294 aas and 7 TMSs.  Transports the plant hormone, gibberellin (GA).  Sweet14 also transports gibberellin.  A double mutant has a defect in anther dehiscence. This mutant also exhibits altered long distant transport of exogenously applied GA and altered responses to GA during germination and seedling stages (Kanno et al. 2016)

Eukaryota
Viridiplantae
SWEET13 of Arabidopsis thaliana (Mouse-ear cress)
*2.A.123.1.27









SWEET transporter 1 of 262 aas and 7 TMSs. Plays a role in the D. officinale symbiotic germination process (Zhang et al. 2016).

Eukaryota
Viridiplantae
Sweet transporter of Dendrobium officinale
*2.A.123.2.1









The 7 TMS (242aa) bacterial MtN3 homologue

Bacteria
Tenericutes
MtN3 homologue of Mycoplasma arthritidis (B3PMT4)
*2.A.123.2.2









3 TMS MtN3 homologue (85aas)

Bacteria
Cyanobacteria
MtN3 of MtN3 of Prochlorococcus marinus (A2BS89)
*2.A.123.2.3









Half sized (3 TMS) bacterial MtN3 protein homologue (85aas)

Bacteria
Fusobacteria
MtN3 homologue of Fusobacterium mortiferum (C3WG44)
*2.A.123.2.4









3 TMS bacterial MtN3 homologue (96aas)

Bacteria
Spirochaetes
MtN3 homologue of Leptospira interrogans (Q8F4F7)
*2.A.123.2.5









3 TMS Sweet homologue, MJ_0110 (93aas)

Archaea
Euryarchaeota
MJ_0110 of Methanocaldococcus jannashii (Q57574)
*2.A.123.2.6









SemiSWEET half glucose transporter of 93 aas and 3 TMSs with an N-terminal amphipathic α-helix.  The protein occurs as a tight homodimer with the translocation channel between the two monomers.  The 3-d structure is known at 2.4 Å resolution revealing the outward open conformation (Xu et al. 2014). The occluded state of the Vibrio sp. N418 SemiSWEET (9.A.58.3.1) has been solved at 1.7 Å resolution (Xu et al. 2014).  The presence of these two states argues in favor of a carrier (rocker switch) mechanism rather than a channel-type mechanism (Xu et al. 2014).

Bacteria
Spirochaetes
SemiSWEET of Leptospira biflexa
*2.A.123.2.7









SemiSWEET homologue of 89 aas and 3 TMSs

Bacteria
Proteobacteria
SemiSWEET of Rickettsia bellii
*2.A.123.2.8









SWEET homologue of 141 aas and 4 putative TMSs.

Bacteria
Cyanobacteria
SWEET homologue of Anabaena variabilis
*2.A.123.2.9









SWEET homologue of 231 aas and 7 TMSs

Bacteria
Tenericutes
SWEET homologue of Mycoplasma hyopneumoniae
*2.A.123.2.10









SWEET homologue of 125 aas and 3 TMSs; resembles 2.A.123.2.3 with all 3 TMSs overlapping.

SWEET homologue of Phytophthora sojae (Soybean stem and root rot agent) (Phytophthora megasperma f. sp. glycines)
*2.A.123.2.11









SWEET homologue of 125 aas and 3 TMSs.  Closely related to 2.A.123.2.10.

Eukaryota
Oomycetes
SWEET homologue of Phytophthora parasitica
*2.A.123.2.12









SWEET homologue of 84 aas and 3 TMSs

Archaea
Euryarchaeota
SWEET homologue of Methanocella conradii
*2.A.123.2.13









Uncharacterized protein of 728 aas and 5 putative TMSs with 4 N-terminal TMSs, where the first 3 are homologous to semisweets of 3 TMSs. The long sequence with one large centrally located peak of hydrophobicity includes several recognized protein domains following the SWEET domain in the following order:  Cache-3 - Cache-1 - dimerization interface domain - HAMP domain - followed by two PAS domains.  Another protein (UniProt acc #I3IJJ5 of 762 aas), has residues 3 - 635 aas) showing 83% sequence identity with residues 96 - 728 in 2.A.123.2.13.

Bacteria
Planctomycetes
UP of Candidatus Jettenia caeni
*2.A.123.2.14









SemiSWEET of 86 aas and 3 TMSs specific for sucrose. The basic unit of SWEETs may be a 3-TMS unit, and it has been suggested that a functional transporter contains at least four such domains, although this suggestion has not been substantiated (Xuan et al. 2013).

Bacteria
Proteobacteria
SemiSWEET of Bradyrhizobium diazoefficiens
*2.A.123.2.15









Putative uncharacterized protein of 99 aas and 3 TMSs

Bacteria
Candidatus Saccharibacteria
Hypothetical protein UW38 of Candidatus Saccharibacteria bacterium
*2.A.123.3.1









SemiSWEET half putative sugar transporter of 97 aas and 3 TMSs with an N-terminal amphipathic α-helix.  The protein occurs as a tight homodimer with the translocation channel between the two monomers.  The 3-d structure is known at 1.7 Å resolution revealing the occluded conformation (Xu et al. 2014). The outward open state of the Leptospira biflexa SemiSWEET (2.a.123.2.6) has been solved at 2.4 Å resolution (Xu et al. 2014).  The presence of these two states argues in favor of a carrier (rocker switch) mechanism rather than a channel-type mechanism (Xu et al. 2014).

Bacteria
Proteobacteria
SemiSWEET of Vibrio sp. N418
*2.A.123.3.2









Uncharacterized protein of 107 aas.

Bacteria
Proteobacteria
UP of Rhodobacteraceae bacterium KLH11
*2.A.123.3.3









Uncharacterized conserved protein of 273 aas and 7 TMSs containing PQ loop repeats.

Bacteria
Actinobacteria
UP of Geodermatophilus obscurus
*2.A.123.3.4









Uncharacterized protein of 97 aas and 3 TMSs.

Bacteria
Proteobacteria
UP of Photobacterium leiognathi
*2.A.123.4.1









Membrane protein of 209 aas and 7 TMSs with a putative N-terminal lipid A disaccharide synthase domain.  This protein is a member of the "Lipid A Biosynthesis, N-terminal (LAB_N) domain in Pfam/CDD, related to the SWEET family.

Bacteria
Bacteroidetes/Chlorobi group
Membrane protein of Gramella forsetii
*2.A.123.4.2









Uncharacterized protein of 115 aas and 3 TMSs.

Bacteria
Proteobacteria
UP of Frateuria aurantia (Acetobacter aurantius)
*2.A.123.4.3









Uncharacterized protein (putative lipid A synthesis protein domain) of 115 aas and 3 TMSs.

Bacteria
Proteobacteria
UP of Stenotrophomonas maltophilia (Pseudomonas maltophilia) (Xanthomonas maltophilia)