title: Expression of inositol 1,4,5-trisphosphate receptors changes the Ca2+ signal of Xenopus oocytes.
abstract: The receptors for the second messenger inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] form a family of closely related proteins that play an important role in regulating the free intracellular Ca2+ concentration. To test the hypothesis that changing the expression level of Ins(1,4,5)P3 receptors could alter the Ins(1,4,5)P3-mediated Ca2+ signal, we overexpressed Ins(1,4,5)P3 receptor type 1 (InsP3R-1) or type 3 (InsP3R-3) in Xenopus laevis oocytes. Expression of InsP3R-1 increased the velocity of the propagating waves of intracellular Ca2+ release but did not affect the Ins(1,4,5)P3-induced entry of extracellular Ca2+ across the plasma membrane. In contrast, expression of intracellular Ca2+ but markedly increased the magnitude and duration of Ca2+ influx. Immunolocalization studied revealed InsP3R-3 at the endoplasmic reticulum, with a relatively stronger signal at or near the plasma membrane. The results suggest that changing the expression level of an InsP3R can alter the Ins(1,4,5)P3-mediated Ca2+ signal and that InsP3R-1 and InsP3R-3 may have different biological functions.
authors.affiliation: Veterans Affairs Medical Center, Iowa City, Iowa, USA.
authors.forename: S
authors.initials: S
authors.lastname: DeLisle
authors.forename: O
authors.initials: O
authors.lastname: Blondel
authors.forename: F J
authors.initials: FJ
authors.lastname: Longo
authors.forename: W E
authors.initials: WE
authors.lastname: Schnabel
authors.forename: G I
authors.initials: GI
authors.lastname: Bell
authors.forename: M J
authors.initials: MJ
authors.lastname: Welsh
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels / Q000378:metabolism*; D005260:Female; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007425:Intracellular Membranes / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D015398:Signal Transduction; D014981:Xenopus
chemical_list: D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium