Regulation of the type III InsP(3) receptor by InsP(3) and calcium |
| |
Authors: | O'Neill Allison F Hagar Robert E Zipfel Warren R Nathanson Michael H Ehrlich Barbara E |
| |
Institution: | Department of Medicine, Yale University, New Haven, CT 06520, USA. |
| |
Abstract: | It has been proposed that the inositol 1,4,5-trisphosphate receptor (InsP(3)R) type III acts as a trigger for InsP(3)-mediated calcium (Ca(2+)) signaling, because this InsP(3) isoform lacks feedback inhibition by cytosolic Ca(2+). We tested this hypothesis in RIN-m5F cells, which express predominantly the type III receptor. Extracellular ATP increases Ca(2+) in these cells, and we found that this effect is independent of extracellular Ca(2+) but is blocked by the InsP(3)R antagonist heparin. There was a dose-dependent increase in the number of cells responding to ATP and two-photon flash photolysis of caged-Ca(2+) heightened the sensitivity of RIN-m5F cells to this increase. These findings provide evidence that Ca(2+) increases the sensitivity of the InsP(3)R type III in intact cells and supports the idea that this isoform can act as a trigger for hormone-induced Ca(2+) signaling. |
| |
Keywords: | Ion channel gating Calcium channels Calcium signaling Lipid bilayers |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|