Characterization of a membrane protein from brain mediating the inhibition of inositol 1,4,5-trisphosphate receptor binding by calcium

摘要: Inositol 1,4,5-trisphosphate (InsP3) is a component of the phosphoinositide second-messenger system which mobilizes Ca2+ from intracellular stores. Recently, an InsP3 receptor binding protein rat cerebellar membranes was solubilized and purified to homogeneity. The potent inhibition by [3H]InsP3 in cellular not apparent receptor. Ca2+-dependent crude homogenate (concn. giving 50% = 300 nM) can be restored addition In present study, we further characterize confers Ca2+-sensitivity receptor, term ‘calmedin’. Calmedin appears neutral membrane with estimated Mr 300,000 gel filtration presence Triton X-100. binding, completely reversed 10 min incubation EDTA therefore does represent proteinase action. effects on depend calmedin, although also binds directly regional distribution calmedin differs that brain, suggesting it mediates other functions. activity peripheral tissues much lower than brain.