Table 1.
Properties of the two arginase isoforms.
| Enzyme | Arginase 1 | Arginase 2 |
|---|---|---|
| Genomic location in mouse | 10; 10 A4 | 12; 12 C3 |
| Number of amino acids | 323 | 354 |
| Genomic location in human | 6q23 | 14q24.1 |
| Number of amino acids | 322 | 354 |
| Sequence identity | ARG2 has 58% sequence identity to ARG1 | |
| Structure | Homotrimer | |
| Catalyzed reaction | L-arg → urea + L-ornithine | |
| Localization | Cytosol | Mitochondrion |
| Tissue specificity | Liver, to a lesser extent kidney | Expressed ubiquitously, mainly kidney and prostate |
| Phenotype of knockout (KO) mice | Lethal, death occurs typically by postnatal day 17 (39). In conditional knockouts, death of adult mice occurs typically after 21 days of KO induction (40) | KO viable and apparently indistinguishable from wild-type mice (41, 42) |
| Phenotype of deficiency in humans | Urea cycle disorder, hyperargininemia, progressive neurologic impairment (43) | Defects not described.ARG2 level is increased in ARG1-deficient patients (43, 44) |
| Effect of ARG on immune response | Immunosuppression (45) | Unclear - immunosuppression (46–49), but also expressed by proinflammatory cells (50–52) |