Bradykinin sequesters B2 bradykinin receptors and the receptor-coupled Ga SUBUNITS Gaq and Gai in caveolae

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Abstract

Caveolae are small flask-like invaginations on the plasma membrane that contain both G-proteins aim G-protein coupled receptors. Consequently, these structures have been implicated to serve a role in transmembrane signaling. Bradykinin (BK) is a potent vasoactive peptide that acts through B2 BK receptors to stimulate both Gaq and Gai. DDT1 MF2 smooth muscle cells were used to show that eaveolae contain both Gaq, Gai and B2 receptors. Ga subunits and caveolin, a marker protein for eaveolae, were monitored by iminunoblotting, while B2 receptors were monitored as receptor radioligand complexes which were formed prior to cell disruption and caveolae enrichment. At 4°C, both agonist and antagonist receptor complexes were detected in eaveolae, and both types of complexes were acid-sensitive. Elevation of the temperature to 37°C resulted in a recruitment of agonist receptor complexes to caveotae and an increased acid-resistance of these complexes. Furthermore, these con ditions also promoted the recruitment of Gaq and Gci subunits. In contrast, antagonist receptor complexes were not recruited and remained acid-sensitive, and antagonists did not recruit Ga subunits. These results show that agonists for some G-protein-coupled receptors sequester their receptors and receptorcoupled Ga subunits in caveolae.

Details

Authors
External organisations
  • University of Manchester
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cell and Molecular Biology
Original languageEnglish
JournalFASEB Journal
Volume11
Issue number9
Publication statusPublished - 1997 Dec 1
Publication categoryResearch
Peer-reviewedYes
Externally publishedYes