Table 4.

Effect of polyanion-binding site and distal site mutations on activation by InsPs

Activator	Fold activation
	IDEwt	IDEK898A,K899A,S901A	IDEY609F
Ins(4,5)P2	7.8	1.6	10
PtdIns(4,5)P2	3.9*	1.7	1.6†
Ins(1,4,5)P3	32.6	6.7	9.4
Phytic acid	68.6	6.4	29.4

Assays were conducted with 50 µM Ins(4,5)P2, 5 µM PtdIns(4,5)P2, 50 µM PtdIns(1,4,5)P3, and 5 µM phytic acid.

^*Based on a concentration range of 0–3 µM above which inhibition was observed (Fig. 3B).

^†Data could not be fit to a hyperbola, because an increase in rate was observed only at 1.5 and 3.0 µM. Reported increase is based on a single value at 3 µM.