biostudies-literatureRosker CWellcome TrustBiotechnology and Biological Sciences Research Council5186-94https://www.ebi.ac.uk/biostudies/studies/S-EPMC2643496biostudies-literatureUnknown284(8)Ryanodine receptors (RyR) are Ca(2+) channels that mediate Ca(2+) release from intracellular stores in response to diverse intracellular signals. In RINm5F insulinoma cells, caffeine, and 4-chloro-m-cresol (4CmC), agonists of RyR, stimulated Ca(2+) entry that was independent of store-operated Ca(2+) entry, and blocked by prior incubation with a concentration of ryanodine that inactivates RyR. Patch-clamp recording identified small numbers of large-conductance (gamma(K) = 169 pS) cation channels that were activated by caffeine, 4CmC or low concentrations of ryanodine. Similar channels were detected in rat pancreatic beta-cells. In RINm5F cells, the channels were blocked by cytosolic, but not extracellular, ruthenium red. Subcellular fractionation showed that type 3 IP(3) receptors (IP(3)R3)The Journal of biological chemistryFunctional ryanodine receptors in the plasma membrane of RINm5F pancreatic beta-cells.PMC2643496BB/E004660/1Rosker CTaylor CWTaylor EJMeur GfalseFunctional ryanodine receptors in the plasma membrane of RINm5F pancreatic beta-cells.Ryanodine receptors (RyR) are Ca(2+) channels that mediate Ca(2+) release from intracellular stores in response to diverse intracellular signals. In RINm5F insulinoma cells, caffeine, and 4-chloro-m-cresol (4CmC), agonists of RyR, stimulated Ca(2+) entry that was independent of store-operated Ca(2+) entry, and blocked by prior incubation with a concentration of ryanodine that inactivates RyR. Patch-clamp recording identified small numbers of large-conductance (gamma(K) = 169 pS) cation channels that were activated by caffeine, 4CmC or low concentrations of ryanodine. Similar channels were detected in rat pancreatic beta-cells. In RINm5F cells, the channels were blocked by cytosolic, but not extracellular, ruthenium red. Subcellular fractionation showed that type 3 IP(3) receptors (IP(3)R3)2009-01-01T00:00:00Z2009 Feb2026-03-16T16:43:57.86Z2019-03-27T00:20:46ZS-EPMC26434961911620710.1074/jbc.M805587200