Comparison of Ins(1,4,5)P 3 receptors from rat cerebellum and bovine adrenal cortex

Abstract

Ins(1,4,5)P 3 receptors in adrenal cortical and cerebellar membranes can be distinguished by their affinities for Ins(1,4,5)P 3 as well as the potencies with which heparin and Mg 2+ inhibit binding. We have found that the differences in Ins(1,4,5)P 3 affinity and heparin inhibition are maintained upon receptor solubilization and purification. In contrast to this, heparin-agarose affinity purification of solubilized cerebellar receptors reduces the potency of Mg 2+ inhibition to that in adrenal cortex. These results suggest that Ins(1,4,5)P 3 receptors in adrenal cortex are structurally distinct from those in cerebellum. Monoclonal antibodies raised against C- and N-terminal regions of mouse cerebellar Ins(1,4,5)P 3 receptors recognize 250–300-kDa proteins in both rat cerebellum and bovine adrenal cortex.