Table 3.
Differential effects of mutagenesis of catalytically-important Gln residues upon 3-kinase and 6-kinase activities of IPMK
Data are mean ± S.E. from 3 to 6 determinations. There was no significant accumulation of Ins(1,4,5,6)P4 in these experiments.
| Mutant | k1 (s−1) InsP3 metabolism | Δ | k2 (s−1) InsP5 synthesis | Δ | k1/k2 |
|---|---|---|---|---|---|
| -fold | -fold | ||||
| None (WT) | 56.1 | 0.64 | 88 | ||
| Q163K | 6.3 ± 0.4 | −9 | 0.41 ± 0.04 | −2 | 16 |
| Q163R | 9.3 ± 0.9 | −6 | 0.68 ± 0.02 | 0 | 14 |
| Q164K | 3.1 ± 0.2 | −18 | 0.31 ± 0.05 | −2 | 10 |
| Q164R | 8.3 ± 0.8 | −7 | 8.5 ± 1.06 | 13 | 1 |
| Q196K | 19.4 ± 1.1 | −3 | 2.4 ± 0.1 | 4 | 8 |
| Q196R | 12.3 ± 1.4 | −4.5 | 3.1 ± 0.4 | 5 | 4 |