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Fig. 2. Scatchard analysis and pharmacological profile of
[3H]-IP3 binding to Drosophila melanogaster
microsomal membrane fractions. Experiments were performed with 100 µg of
microsomal protein and the presence of 1-120 nM (A) or 3 nM
[3H]-IP3 (B) as described in Materials and Methods.
Panel A illustrates a hyperbolic saturation curve as a function of increasing
IP3 concentrations. The inset shows a linear Scatchard plot. This
is a representative experiment from a total of 5. Panel B depicts the
inhibitory effect of 1 mg/ml heparin, 75 µM 2-APB and 5 µM xestospongin
C on [3H]-IP3 binding. The results in Panel B are
expressed as mean±s.e.m. of at least four independent experimental
observations.