Differential regulation of Ca2+ release-activated Ca2+ influx by heterotrimeric G proteins

Xin Xu, Kenichiro Kitamura, Kim S. Lau, Shmuel Muallem, R. Tyler Miller

Research output: Contribution to journalArticle

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Abstract

The least understood aspect of the agonist-induced Ca2+ signal is the activation and regulation of the Ca2+ release-activated Ca2+ influx (CRAC) across the plasma membrane. To explore the possible role of heterotrimeric G proteins in the various regulatory mechanisms of CRAC, continuous renal epithelial cell lines stably expressing α13 and the constitutively active αqQ209L were isolated and used to measure CRAC activity by the Mn2+ quench technique. Release of intracellular Ca2+ by agonist stimulation or thapsigargin was required for activation of CRAC in all cells. Although the size of the internal stores was similar in all cells, CRAC was 2-3-fold higher in α13- and αqQ209L-expressing cells. However, the channel was differentially regulated in the two cell types. Incubation at low [Ca2+]i, inhibition of the NOS pathway, or inhibition of tyrosine kinases inhibited CRAC activity in α13 but not αqQ209L cells. Treatment with okadaic acid prevented inhibition of the channel by low [Ca2+]i and the protein kinase inhibitors in α13 cells. These results suggest that expression of αqQ209L dominantly activates CRAC by stabilizing a phosphorylated state, whereas expression of α13 makes CRAC activation completely dependent on phosphorylation by several kinases. G proteins may also modulate CRAC activity independently of the phosphorylation/ dephosphorylation state of the pathway to increase maximal CRAC activity. Furthermore, our results suggest a general mechanism for regulation of CRAC that depends on coupling of receptors to specific G proteins.

Original languageEnglish (US)
Pages (from-to)29169-29175
Number of pages7
JournalJournal of Biological Chemistry
Volume270
Issue number49
StatePublished - Dec 8 1995

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Heterotrimeric GTP-Binding Proteins
Phosphorylation
Chemical activation
GTP-Binding Proteins
Okadaic Acid
Thapsigargin
Cell membranes
Protein Kinase Inhibitors
Protein-Tyrosine Kinases
Phosphotransferases
Epithelial Cells
Cell Membrane
Kidney
Cell Line

ASJC Scopus subject areas

  • Biochemistry

Cite this

Differential regulation of Ca2+ release-activated Ca2+ influx by heterotrimeric G proteins. / Xu, Xin; Kitamura, Kenichiro; Lau, Kim S.; Muallem, Shmuel; Miller, R. Tyler.

In: Journal of Biological Chemistry, Vol. 270, No. 49, 08.12.1995, p. 29169-29175.

Research output: Contribution to journalArticle

Xu, Xin ; Kitamura, Kenichiro ; Lau, Kim S. ; Muallem, Shmuel ; Miller, R. Tyler. / Differential regulation of Ca2+ release-activated Ca2+ influx by heterotrimeric G proteins. In: Journal of Biological Chemistry. 1995 ; Vol. 270, No. 49. pp. 29169-29175.
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