Table 2.
Main differences between IDO1 and IDO2 in humans.
| hIDO1 | hIDO2 | Reference | |
|---|---|---|---|
| Tissue mRNA expression in physiological conditions | Lung endothelial cells, secondary lymphoid organs, placenta |
Liver, placenta | [37,78] |
| Regulatory stimuli | IFNγ, PGE2, LPS, IL-1β, IL-6, TGFβ, spermidine |
IFNγ, IL-10, PGE2, LPS | [68,71,72,73,75,76] |
| L-Trp binding affinity (Km) | 20.90 ± 3.91 μM | 6809 ± 917 μM 9360 ± 810 μM |
[28,29] |
| L-Trp catalytic constant (Kcat) | 2.97 ± 0.20 s−1 | 0.103 ± 0.006 s−1 | [28] |
| ITIM consensus motif | ITIM1 | ITIM1 | [21,24,46] |
| VPY(111)CQL | IFY(231)AGI | ||
| ITIM2 | ITIM2 | ||
| LVY(249)EGF | LMY(253)EGV | ||
| YENM (PI3K binding motif) | Y(145)ENM | Absent | [22,46] |
| Molecular binding partner | SHP1 | Absent | [21,22,23,24] |
| SHP2 | Absent | ||
| SOCS3 | Absent | ||
| PI3K | Absent | ||
| Physiological role | Immune regulation via Trp-catalysis and signaling function |
Not defined, low Trp enzymatic activity |
[5,21,70] |