Ins(1,3,4,5)P4 has been suggested to be involved in cellular Ca2+ signalling. A receptor from pig cerebellar membranes, which binds InsP4 with high affinity and selectivity [Donié & Reiser (1989) FEBS Lett. 254, 155-158], has been solubilized and purified about 20,000-fold by chromatography using CM-cellulose, heparin-agarose and hydroxyapatite. The InsP4 receptor, identified by SDS/PAGE, had an apparent molecular mass of 42 kDa and bound 4.6 nmol of InsP4 per mg of protein, with a dissociation constant of 5.6 nM.
