RGD Reference Report - Selective phosphorylation of the IP3R-I in vivo by cGMP-dependent protein kinase in smooth muscle. - Rat Genome Database

Send us a Message



Submit Data |  Help |  Video Tutorials |  News |  Publications |  Download |  REST API |  Citing RGD |  Contact   

Selective phosphorylation of the IP3R-I in vivo by cGMP-dependent protein kinase in smooth muscle.

Authors: Murthy, KS  Zhou, H 
Citation: Murthy KS and Zhou H, Am J Physiol Gastrointest Liver Physiol 2003 Feb;284(2):G221-30.
RGD ID: 729122
Pubmed: PMID:12529267   (View Abstract at PubMed)
DOI: DOI:10.1152/ajpgi.00401.2002   (Journal Full-text)

This study examined the expression of inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R) types and PKG isoforms in isolated gastric smooth muscle cells and determined the ability of PKG and PKA to phosphorylate IP(3)Rs and inhibit IP(3)-dependent Ca(2+) release, which mediates the initial phase of agonist-induced contraction. PKG-Ialpha and PKG-Ibeta were expressed in gastric smooth muscle cells, together with IP(3)-R-associated cG-kinase substrate, a protein that couples PKG-Ibeta to IP(3)R-I. IP(3)R-I and IP(3)R-III were also expressed, but only IP(3)R-I was phosphorylated by PKA and PKG in vitro and exclusively by PKG in vivo. Sequential phosphorylation by PKA and by PKG-Ialpha in vitro showed that PKA phosphorylated the same site as PKG (presumably S(1755)) and an additional PKA-specific site (S(1589)). In intact muscle cells, agents that activated PKG or both PKG and PKA induced IP(3)R-I phosphorylation that was reversed by the PKG inhibitor (8R,9S,11s)-(-)-9-methoxy-carbamyl-8-methyl-2,3,9,10-tetrahydro-8,11-epoxy -1H,8H,1H,-2,7b,11a-trizadizo-benzo9(a,g)cycloocta(c,d,e)-trinden-1-one. Agents that activated PKA induced IP(3)R-I phosphorylation in permeabilized but not intact muscle cells, implying that PKA does not gain access to IP(3)R-I in intact muscle cells. The pattern of IP(3)R-I phosphorylation in vivo and in vitro was more consistent with phosphorylation by PKG-Ialpha. Phosphorylation of IP(3)R-I in microsomes by PKG, PKA, or a combination of PKG and PKA inhibited IP(3)-induced Ca(2+) release to the same extent, implying that inhibition was mediated by phosphorylation of the PKG-specific site. We conclude that IP(3)R-I is selectively phosphorylated by PKG-I in intact smooth muscle resulting in inhibition of IP(3)-dependent Ca(2+) release.

Objects referenced in this article
Gene Itpr3 inositol 1,4,5-trisphosphate receptor, type 3 Rattus norvegicus

Additional Information