Table 1.
Summary of subfamilies identified within the NSS family.1
| Subfamily Designation | Description | Number of Sequences |
| Osmolytes | Two distinct groups of GABA transporters (11 and 12, respectively). Also includes: creatine (6), taurine (9), and betaine transporters (6). Two remain ORFans. | 46 |
| Biogenic amines | Two distinct groups of dopamine transporters (13 and 6, respectively). Also includes: norepinephrine (13), epinephrine (1), and serotonin (11) transporters. | 44 |
| Renal system | Only 7 sequences are characterized, of which: 5 are isolated from the renal system; 1 is an intestinal brush border proline transporter; and the last was found in the brain. Due to the location of the branch point, the sequences highlighted in dark purple in Figure 1 are also included; however, no experimental evidence is available to confirm or refute this. | 24 |
| Amino acid #1 | Mainly includes proline (5) and glycine (10) transporters; 3 are generically annotated as "amino acid" transporters. | 18 |
| Amino acid #2 | 3 generically annotated as "amino acid" transporters and 2 ORFans. | 5 |
| Prokaryotic | Bacterial and archaeal transporters (includes LeuTAa). Nearly all are from genome sequencing projects and lack robust biophysical characterization of functional specificity. | 44 |
1 An exact summary of all experimentally characterized and ORFan sequences are provided in Additional file 1.