Table 1

Effects of Ins(1,4,5)P 3, adenophostin, and its analogs on 3H-Ins(1,4,5)P 3 binding and Ca2+ mobilization

Cerebellum BindingLiver BindingLiver Ca++Mobilization
KdhKdhEC50h
nM nM nM
Natural adenophostin A0.92  ± 0.081.44  ± 0.10.86  ± 0.201.28  ± 0.3710.9  ± 0.72.18  ± 0.39
Synthetic adenophostin A1.22  ± 0.111.25  ± 0.01.60  ± 0.371.18  ± 0.0912.3  ± 0.32.36  ± 0.13
Ins(1,4,5)P3 6.83  ± 0.780.91  ± 0.037.96  ± 1.021.02  ± 0.08153  ± 112.25  ± 0.20
Acyclophostin (3)3.83  ± 0.480.97  ± 0.102.76  ± 0.261.12  ± 0.17209  ± 122.48  ± 0.18
4 N.D.1-a 161  ± 240.98  ± 0.11870  ± 662.51  ± 0.14
1 N.D. 1-a 2,650  ± 4900.54  ± 0.0333,300  ± 3,5003.05  ± 0.39
2 N.D. 1-a 4,2200.43Inactive at 100 μM
5 N.D. 1-a Inactive at 100 μMInactive at 100 μM

Experiments similar to those shown in Fig. 2 were used to determine theK d from equilibrium competition binding experiments with 3H-Ins(1,4,5)P 3 (pH 8.3, 2°C) and the EC50 from45CA++ flux assays (pH 7, 37°C) for each of the indicated compounds. Results are expressed as means ± S.E.M. of 3 to 16 (n = 1, for binding with 2) independent experiments with duplicate determinations for each. The results of similar equilibrium competition binding experiments with rat cerebellar membranes performed under identical conditions to those used for hepatic membranes are shown for some of the compounds (n = 3–16).

    • ↵1-a N.D., not determined.