TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameDomainKingdom/PhylumProtein(s)
*2.A.39.1.1









Cytosine permease
Bacteria
Proteobacteria
CodB of E. coli (P0AA82)
*2.A.39.1.2









The putative hydroxymethylpyrimidine transporter, CytX (Rodionov et al. 2002)

Bacteria
Proteobacteria
CytX of Pseudomonas putida (B1JAG2)
*2.A.39.1.3









The putative hydroxymethylpyrimidine porter, CytX (Rodionov et al., 2002

Bacteria
Proteobacteria
CytX of Neisseria meningitidis (A1KWE6)
*2.A.39.1.4









Putative nucleobase transporter

Bacteria
Firmicutes
Putative nucleobase transporter of Alicyclobacillus acidocaldarius (F8IKT4)
*2.A.39.1.5









Putative purine-cytosine permease yxlA
Bacteria
Firmicutes
yxlA of Bacillus subtilis
*2.A.39.1.6









Bacteria
Actinobacteria
*2.A.39.1.7









Bacteria
Actinobacteria
*2.A.39.2.1









Cytosine-purine permease
Eukaryota
Fungi
Fcy2 of Saccharomyces cerevisiae (P17064)
*2.A.39.2.2









The vitamin B6:H+ symporter, Tpn1 (pyridoxine, pyridoxal and pyridoxamine are substrates) (Stolz and Vielreicher, 2003)
Eukaryota
Fungi
Tpn1 of Saccharomyces cerevisiae (P53099)
*2.A.39.2.3









The hypoxanthine/adenine/guanine (purine) transporter, Fcy21 (Goudela et al., 2006)
Eukaryota
Fungi
Fcy21 of Candida albicans (Q708J7)
*2.A.39.2.4









The cytosine-purine-scavenging protein, FcyB (low capacity, high affinity; 45% identical and maybe orthologous to the yeast purine-cytosine protein (2.A.39.2.3) (Vlanti and Diallinas 2008).  Substrate docking and mutational analyses have revealed residues essential for specificity and function (Krypotou et al. 2012).

Eukaryota
Fungi
FycB of Aspergillus nidulans (B1PXD0)
*2.A.39.3.1









Allantoin permease
Eukaryota
Fungi
Dal4 of Saccharomyces cerevisiae
*2.A.39.3.2









Uracil/uridine permease
Eukaryota
Fungi
Fur4 of Saccharomyces cerevisiae
*2.A.39.3.3









Uridine (nucleoside; fluorouridine; not uracil or allantoin) permease, Fui1 (Uridine:H+ (1:1) symporter) (inhibited by analogues with modifications at positions C5') (Zhang et al., 2006)
Eukaryota
Fungi
Fui1 (YBL042; YBC2) of Saccharomyces cerevisiae
*2.A.39.3.4









Allantoin permease, PucI, with 12 TMSs and both N- and C-termin on the inside. PucI transports allantoin with a Km of 24 mυM, but recognizes some additional hydantoin compounds, including hydantoin itself, and to a lesser extent a range of nucleobases and nucleosides (Ma et al. 2016).

Bacteria
Firmicutes
PucI (YwoE) of Bacillus subtilis
*2.A.39.3.5









The probable hydantoin permease, HyuP (most similar to the hydantoin transporter of Microbacterium liquefaciens; Suzuki and Henderson, 2006)
Bacteria
Actinobacteria
HyuP of Arthrobacter aurescens (Q9F467)
*2.A.39.3.6









The benzyl-hydantoin:cation symporter-1, Mhp1 (84% identical to 2.A.39.3.5).  The 3-d structures in the open and closed states (2.85 Å resolution) are known (Weyand et al., 2008). Models of the ion-coupled coonformational cycle have been proposed (Kazmier et al. 2014).

Bacteria
Actinobacteria
Mhp1 of Microbacterium liguefaciens
(2JLN_A) (210060745)
*2.A.39.3.7









Uracil permease
Eukaryota
Fungi
Fur4 of Schizosaccharomyces pombe
*2.A.39.3.8









Allantoin permease; encoded in an operon with allantoinase and other degradative enzymes (Moraes and Reithmeier 2012).

Bacteria
Proteobacteria
YbbW of Escherichia coli
*2.A.39.3.9









NCS-1 homologue of unknown function and of 652 aas with 14 TMSs in a 2 + 2 + 2... arrangment.

Eukaryota
Bangiophyceae
NCS-1 homologue of Galdieria sulphuraria
*2.A.39.3.10









Uracil uptake porter, FurD of 544 aas (Krypotou et al. 2015).

Eukaryota
Fungi
FurD of Emericella nidulans (Aspergillus nidulans)
*2.A.39.3.11









Purine/uracil uptake porter of 599 aas and 12 TMSs, NCS1 or PLUTO.  Nucleobase:proton symporter that facilitates the uptake of nucleobases in the cells. Can transport adenine, guanine and uracil (Witz et al. 2014). Contributes to uracil import into plastids for plastidic uracil salvage which is essential for plant growth and development (Witz et al. 2012).

Eukaryota
Viridiplantae
PLUTO of Arabidopsis thaliana (Mouse-ear cress)
*2.A.39.3.12









NCS1 of 540 aas and 12 TMSs.  Transports adenine, guanine, hypoxanthine, cytosine, and allantoin and competitively binds xanthine and uric acid. The closely related Zea mays NCS1 transports adenine, guanine, and cytosine and competitively binds, 5-fluorocytosine, hypoxanthine, xanthine, and uric acid. The differences in these NCS1 profiles are due to a limited number of amino acid differences (Rapp et al. 2016).

NCS1 of Setaria viridis (Green bristlegrass) (Setaria italica subsp. viridis)
*2.A.39.3.13









Uracil-specific permease of 581 aas and 11 or 12 TMSs. FUR4.  Deletion of the FUR4 gene confers resistance to 5-fluorouracil as well as cross-resistance to triazoles and imidazole antifungal agents when they are used simultaneously with 5-fluorouracil although the nucleobase transporters are not involved in azole uptake. Only fluorinated pyrimidines, not pyrimidines themselves, are able to promote cross-resistance to azoles by both the salvage and the de novo pathway of pyrimidine synthesis. Subinhibitory doses of 5-fluorocytosine, 5-fluorouracil, and 5-fluorouridine also trigger resistance to fluconazole in susceptible wild-type strains of C. lusitaniae and of different Candida species. Thus, intracellular fluorinated nucleotides play a role in azole resistance, either by preventing azoles from targeting the catalytic site of lanosterol 14-alpha-demethylase or by acting as a molecular switch for the triggering of efflux transport (Gabriel et al. 2014; ).

Eukaryota
Fungi
FUR4 of Clavispora lusitaniae (Candida lusitaniae)
*2.A.39.3.14









NCS1 of 528 aas and 12 TMSs.  Transporter of adenine, guanine, uracil and allantoin (Schein et al. 2013).

Eukaryota
Viridiplantae
NCS1 of Chlamydomonas reinhardtii (Chlamydomonas smithii)
*2.A.39.4.1









Thiamine permease, Thi10
Eukaryota
Fungi
Thi10 of Saccharomyces cerevisiae
*2.A.39.4.2









The nicotinamide riboside transporter, Nrt1 (Belenky et al., 2008)
Eukaryota
Fungi
Nrt1 of Saccharomyces cerevisiae (Q08485)
*2.A.39.5.1









The putative mannitol porter, MtlP (Rodionov et al. 2010).

Bacteria
Proteobacteria
MtlP of Shewanella frigidimarina (Q082R8)