Table 2.
Eukaryotic ABC transporters classified according to their TMD foldsa.
| TMD fold | TM helix organization |
Experimentally determined structures |
PDB codesb | Function |
|---|---|---|---|---|
| Type IV | 6 + 6 Homodimer Heterodimer Single chain |
ABCB subfamily | ||
| P-gp (ABCB1) | 4F4C, 4M1M, 4M2S, 4M2T, 4Q9H, 4Q9I, 4Q9J, 4Q9K, 4Q9L, 4XWK, 5KPD, 5KPI, 5KPJ, 5KO2, 5KOY, 6C0V | Multidrug export | ||
| CmABCB1 | 3WME, 3WMF, 3WMG, 6A6M, 6A6N | Multidrug export | ||
| ScAtm1 (ABCB7) | 4MYC, 4MYH | Unknown substrate for Fe/S protein biogenesis | ||
| TAP1/2 (ABCB2/3) | 5U1D | Peptide export | ||
| ABCB4 | 6S7P | Lipid export | ||
| ABCB8 | 5OCH | Unknown | ||
| ABCB10 | 3ZDQ, 4AYT, 4AYW, 4AYX | Unknown | ||
| ABCB11 | 6LR0 | Bile salt export | ||
| ABCC subfamily | ||||
| MRP1 (ABCC1) | 5UJA, 5UJ9, 6BHU, 6UY0 | Leukotriene, sphingolipid, and multidrug export | ||
| CFTR (ABCC7) | 5UAR, 5UAK, 5W81, 6D3R, 6MSM, 6O1V, 6O2P | Chloride channel | ||
| SUR1 (ABCC8) | 6BAA, 6C3O, 5YKE, 5YKF, 5YWC, 5YWD, 5YW7, 5YW8, 6JB1, 6JB3, 6PZ9,6PZA, 6PZC, 6PZI | Regulatory module of KATP channel | ||
| ABCD subfamily | ||||
| ABCD4 | 6JBJ | Cobalamin import | ||
| Type V | 6 + 6 Homodimer Heterodimer Single chain |
ABCA subfamily | ||
| ABCA1 | 5XJY | Phospholipid/cholesterol export | ||
| ABCG subfamily | ||||
| ABCG5/8 | 5DO7 | Sterol export | ||
| ABCG2 | 5NJG, 5NJ3, 6ETI, 6FEQ, 6FFC, 6HIJ, 6HCO, 6HBU, 6HZM, 6VXF, 6VXH, 6VXI, 6VXJ | Multidrug export |
a
Excluding ABC proteins of the ABCH and ABCI subfamilies, which most likely can be classified as type V and type III systems, respectively.
b
Only PDB codes of structures with an overall resolution equal to or better than 4.5 Å were included.