scholarly journals Regulation of Inositol 1,4,5 Trisphosphate Receptors by InsP3 Receptor-Associated cGMP Kinase Substrate (IRAG)

2010 ◽  
Vol 98 (3) ◽  
pp. 514a
Author(s):  
Wataru Masuda ◽  
Matthew J. Betzenhauser ◽  
David I. Yule
Keyword(s):  
Kinase Substrate ◽  
Inositol 1,4,5 Trisphosphate ◽  
Insp3 Receptor

Investigation of the roles of Ca2+ and InsP3 diffusion in the coordination of Ca2+ signals between connected hepatocytes

2001 ◽  
Vol 114 (11) ◽  
pp. 1999-2007
Author(s):  
Caroline Clair ◽  
Cécile Chalumeau ◽  
Thierry Tordjmann ◽  
Josiane Poggioli ◽  
Christophe Erneux ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Significant Role ◽  
Signaling Molecules ◽  
Rat Hepatocyte ◽  
Inositol 1,4,5 Trisphosphate ◽  
Gap Junction Coupling ◽  
Junction Coupling ◽  
Insp3 Receptor

Glycogenolytic agonists induce coordinated Ca2+ oscillations in multicellular rat hepatocyte systems as well as in the intact liver. The coordination of intercellular Ca2+ signals requires functional gap-junction coupling. The mechanisms ensuring this coordination are not precisely known. We investigated possible roles of Ca2+ or inositol 1,4,5-trisphosphate (InsP3) as a coordinating messengers for Ca2+ spiking among connected hepatocytes. Application of ionomycin or of supra-maximal concentrations of agonists show that Ca2+ does not significantly diffuse between connected hepatocytes, although gap junctions ensure the passage of small signaling molecules, as demonstrated by FRAP experiments. By contrast, coordination of Ca2+ spiking among connected hepatocytes can be favored by a rise in the level of InsP3, via the increase of agonist concentrations, or by a shift in the affinity of InsP3 receptor for InsP3. In the same line, coordination cannot be achieved if the InsP3 is rapidly metabolized by InsP3-phosphatase in one cell of the multiplet. These results demonstrate that even if small amounts of Ca2+ diffuse across gap junctions, they most probably do not play a significant role in inducing a coordinated Ca2+ signal among connected hepatocytes. By contrast, coordination of Ca2+ oscillations is fully dependent on the diffusion of InsP3 between neighboring cells.

scholarly journals Functional osteoclast attachment requires inositol-1,4,5-trisphosphate receptor-associated cGMP-dependent kinase substrate

2010 ◽  
Vol 90 (10) ◽  
pp. 1533-1542 ◽  
Author(s):  
Beatrice B Yaroslavskiy ◽  
Irina Turkova ◽  
Yujuan Wang ◽  
Lisa J Robinson ◽  
Harry C Blair
Keyword(s):  
Kinase Substrate ◽  
Inositol 1,4,5 Trisphosphate ◽  
Trisphosphate Receptor

Interactions Between the Inositol 1,4,5-Trisphosphate and Cyclic AMP Signaling Pathways Regulate Larval Molting in Drosophila

Genetics ◽  
2001 ◽  
Vol 158 (1) ◽  
pp. 309-318 ◽  
Author(s):  
K Venkatesh ◽  
G Siddhartha ◽  
Rohit Joshi ◽  
Sonal Patel ◽  
Gaiti Hasan
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Signaling Pathways ◽  
Feedback Inhibition ◽  
Receptor Gene ◽  
Dominant Negative ◽  
Neural Signals ◽  
Inositol 1,4,5 Trisphosphate ◽  
Kinase A ◽  
Insp3 Receptor

Abstract Larval molting in Drosophila, as in other insects, is initiated by the coordinated release of the steroid hormone ecdysone, in response to neural signals, at precise stages during development. In this study we have analyzed, using genetic and molecular methods, the roles played by two major signaling pathways in the regulation of larval molting in Drosophila. Previous studies have shown that mutants for the inositol 1,4,5-trisphosphate receptor gene (itpr) are larval lethals. In addition they exhibit delays in molting that can be rescued by exogenous feeding of 20-hydroxyecdysone. Here we show that mutants for adenylate cyclase (rut) synergize, during larval molting, with itpr mutant alleles, indicating that both cAMP and InsP3 signaling pathways function in this process. The two pathways act in parallel to affect molting, as judged by phenotypes obtained through expression of dominant negative and dominant active forms of protein kinase A (PKA) in tissues that normally express the InsP3 receptor. Furthermore, our studies predict the existence of feedback inhibition through protein kinase A on the InsP3 receptor by increased levels of 20-hydroxyecdysone.

scholarly journals Isolation and characterization of vascular smooth muscle inositol 1,4,5-trisphosphate receptor

1996 ◽  
Vol 316 (1) ◽  
pp. 295-302 ◽  
Author(s):  
Md. Omedul ISLAM ◽  
Yutaka YOSHIDA ◽  
Takaki KOGA ◽  
Masayasu KOJIMA ◽  
Kenji KANGAWA ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Biochemical Properties ◽  
Pcr Analysis ◽  
Binding Property ◽  
Dependent Manner ◽  
Calmodulin Binding ◽  
Isolation And Characterization ◽  
Inositol 1,4,5 Trisphosphate ◽  
Insp3 Receptor

myo-Inositol 1,4,5-trisphosphate (InsP3) receptor of porcine aorta was purified to near homogeneity and its biochemical properties were compared with those of cerebellar InsP3 receptor of the same animal species. The aortic InsP3 receptor consisted of equal amounts of two polypeptides with slightly differing molecular masses of around 240 kDa and was found to possess a single population of InsP3-binding site (Kd of 1.2 nM). The InsP3 receptor purified from porcine cerebellum was also comprised of two polypeptides. However, the molecular mass was slightly but definitely larger, being 250 kDa, and the amounts of the two polypeptides were not equal. The aortic InsP3 receptor cross-reacted with polyclonal antibody specific to type 1 InsP3 receptor as did the cerebellar InsP3 receptor. The aortic InsP3 receptor bound to calmodulin–Sepharose in a Ca2+-dependent manner, while the cerebellar InsP3 receptor did not. Reverse transcriptase-PCR analysis revealed two splicing variants of the type 1 InsP3 receptor in porcine aortic smooth muscle distinct from those of the type 1 InsP3 receptor of porcine cerebellum. The possible relevance of this difference to difference in calmodulin-binding property was discussed.

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