Antibodies to the αq subfamily of guanine nucleotide-binding regulatory protein α subunits attenuate activation of phosphatidylinositol 4,5-bisphosphate hydrolysis by hormones

Stephen Gutowski, Alan Smrcka, Lisa Nowak, Dianging Wu, Melvin Simon, Paul C. Sternweis

Research output: Contribution to journalArticlepeer-review

299 Scopus citations

Abstract

The subfamily of guanine nucleotide-binding regulatory (G proteins) designated Gq has been shown to regulate the activity of phospholipase C by reconstitution. However, the role of these proteins in hormonal regulation of this activity has not been demonstrated. Two antisera were used in attempts to interrupt this pathway. Antiserum W082, developed against a peptide representing an internal sequence in αq, was specific for αq by immunoblots but did not recognize the native protein. Antiserum X384 was developed against a peptide representing the 12 amino acids of the common car boxy 1 termini of αq and α11. It had a broader specificity for this subfamily of G protein α subunits and recognized the native proteins. Antiserum X384 specifically immunoprecipitated αq and its homologs from purified preparations and detergent extracts of membranes. Affinity-purified antibodies attenuated stimulation of phosphatidylinositide 4,5-bisphosphate hydrolysis by bradykinin, angiotensin, and histamine in membranes derived from NG108-15 cells, rat liver, and 1321N1 cells, respectively. Activation of the phospholipase C activity by guanosine 5′-3-O-(thio)triphosphate alone was also inhibited. Inclusion of the peptide to which the antisera were raised blocked the effect of the antibody. In contrast, affinity-purified W082, which did not recognize native proteins, did not alter regulation of phospholipase C. This indicates that the Gq family of signaling proteins can couple to several receptors and is responsible for the hormonal regulation of phospholipase C in these diverse systems. The further generality of this regulatory pathway remains to be established.

Original languageEnglish (US)
Pages (from-to)20519-20524
Number of pages6
JournalJournal of Biological Chemistry
Volume266
Issue number30
StatePublished - 1991

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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