| TCID | Name | Organismal Type | Example |
|---|---|---|---|
| 2.A.40.1.1 | Uracil permease | Bacteria | UraA of E. coli (P0AGM7) |
| 2.A.40.1.2 | High affinity uracil permease | Bacteria | PyrP of Lactococcus lactis (gbCAB89870) |
| 2.A.40.1.3 | Putative pyrimidine permease, RutG (Loh et al., 2006) | Bacteria | RutG of E. coli (P75892) |
| 2.A.40.2.1 | Purine permease | Bacteria | YcpX of Clostridium perfringens |
| 2.A.40.3.1 | Xanthine permease | Bacteria | PbuX (XanP) of Bacillus subtilis |
| 2.A.40.3.2 | Uric acid permease | Bacteria | PucJ of Bacillus subtilis |
| 2.A.40.3.3 | Xanthine permease, YgfO (Karatza et al., 2006). Ile432 and Asn430 in helix 7 are important for xanthine binding (Papakostas et al., 2008). | Bacteria | YgfO of E. coli (P67444) |
| 2.A.40.4.1 | High affinity uric acid-xanthine permease, UapA | Fungi | UapA of Emericella nidulans |
| 2.A.40.4.2 | The putative xanthine permease, YicE (Karatza and Frillingos, 2005) | Bacteria | YicE of E. coli (POAGM9) |
| 2.A.40.5.1 | General purine permease, UapC | Fungi | UapC of Emericella nidulans |
| 2.A.40.6.1 | L-ascorbate:Na+ symporter, SVCT1. (L-ascorbate:Na+= 1:2; Mackenzie et al., 2008) | Animals | SVCT1 of Rattus norvegicus |
| 2.A.40.6.2 | Ca2+/Mg2+-dependent L-ascorbate:Na+ symporter, SVCT2; Na+:ascorbate = 2:1; binding order: Na+, ascorbate, Na+ (Na+ increases the affinity for ascorbate; Ca2+/Mg2+ are required for function) (Godoy et al., 2007). | Animals | SVCT2 of Homo sapiens (Q9WTW8) |
| 2.A.40.6.3 | High affinity (Km = 30 µM) uric acid-xanthine transporter; leaf permease protein 1, LPE1 (necessary for proper chloroplast development in maize) (Argyrou et al., 2001) | Plants | LPE1 of Zea mays (Q41760) |
