| TCID | Name | Organismal Type | Example |
|---|---|---|---|
| 2.A.44.1.1 | Formate efflux permease (catalyzes bidirectional transport, has a pentameric structure, and may function by a channel-type mechanism (Falke et al., 2009)). The structure at Å resolution has been determined (Wang et al., 2009). | Bacteria | FocA of E. coli (P0AC23) |
| 2.A.44.2.1 | Probable formate uptake permease | Bacteria | FdhC of Methanobacterium thermoformicium |
| 2.A.44.3.1 | Nitrite uptake permease | Bacteria | NirC of E. coli (P0AC26) |
