Table 1.
Primary Eukaryotic Cargo Adaptors
| Cargo adaptor | Primary trafficking pathway | Number of subunits in cargo adaptor a | Coat or scaffold | Primary GTPase and lipid regulator(s) |
|---|---|---|---|---|
| AP-1 | TGN-to-EE, EE/RE-to-PM | 4 | clathrin | Arf1 b, PI(4)P |
| AP-2 | Endocytosis | 4 | clathrin | PI(4,5)P2 |
| AP-3 | TGN-to-lysosome, EE-to-lysosome | 4 | clathrin | Arf1 b |
| AP-4 | TGN-to-EE | 4 | none known | Arf1 b |
| AP-5 | LE-to-TGN | 4 | SPG11/15 | PI(3)P |
| BBSome/IFT complexes | Ciliary trafficking | Unresolved c | Unresolved c | Arl6 (aka BBS3) |
| F-subcomplex (COPI) | Golgi, Golgi-to-ER | 4 | α-COP β′-COP ε-COP (B-subcomplex) |
Arf1 b |
| GGA1 | TGN-to-LE | 1 | clathrin | Arf1 b, PI(4)P |
| GGA2 | TGN-to-LE | 1 | clathrin | Arf1 b, PI(4)P |
| GGA3 | TGN-to-LE, RE-to-PM | 1 | clathrin | Arf1 b, Arf6, PI(4)P |
| ESCRT | MVB (LE) sorting | ESCRT-0: 2 ESCRT-I: 4 ESCRT-II: 4 |
ESCRT-III | PI(3)P |
| Exomer | TGN-to-PM | 4 (dimer of dimers) | none known | Arf1 b |
| Retromer | EE-to-TGN, LE-to-TGN | 3 | Vps5 (Snx1) Vps17 (Snx2) |
Rab7, PI(3)P |
| Sec23/24 (COPII) | ER-to-Golgi | 2 | Sec13/31 | Sar1 |
| Snx4/41/42 | EE-to-TGN, EE/RE-to-PM | 3 | none known | Rab11? |
| TSET | Endocytosis | 4 | TTRAY | none known |
a
Note that some subunits have multiple paralogs in some organisms, and for some complexes the number of subunits varies among organisms.
b
Arf1 denotes the paralogous Arf1-5 proteins.
c
The BBSome has 8 subunits, the IFT-A complex has ~6 subunits, and the IFT-B complex has ~14 subunits. It remains to be determined which subunits are involved in cargo recognition and which subunits are involved in scaffolding.