Related Experiment Video
Updated: Aug 17, 2026

Receptor Autoradiography Protocol for the Localized Visualization of Angiotensin II Receptors
Published on: June 7, 2016
Constitutive activity of human angiotensin II type-1 receptors by Gq overexpression
Jason L Scragg1, Philip Warburton, Stephen G Ball
1CRISTAL (Cardiovascular Research Institute at Leeds), School of Medicine, University of Leeds, Leeds LS2 9JT, UK. J.Scragg@leeds.ac.uk
Abstract:
We have developed an inducible HEK293/Tet-On cell line that transiently expresses both FLAG-tagged human angiotensin II type-I receptors (FLAG-hAT(1)R) and G(q)alpha G protein subunits in response to doxycycline. High and tightly regulated levels of FLAG-hAT(1)R (740+/-57 fmol/mg protein) and G(q)alpha (36-fold increase compared with non-induced cells) overexpression were consistently achieved. We investigated the possibility of using an inducible system to increase the proportion of constitutively active wild-type FLAG-hAT(1)Rs by overexpressing G(q)alpha. Following doxycycline treatment, we observed no significant change in the apparent binding affinity or potency (coupling efficiency) of angiotensin II, though significant increases in the intrinsic activity of several partial agonists were observed, indicative of constitutive activity. DUP753 (10 microM), a suggested inverse agonist, did not inhibit the enhanced level of basal (agonist-independent) activity. The data suggest that the resting equilibrium of hAT(1) receptors between the inactive (R) and active (R*) forms is predominantly weighted towards the inactive conformation.
Related Concept Videos
Antihypertensive Drugs: Angiotensin II Receptor Blockers
GPCRs Regulate Adenylyl Cylase Activity
Two...
Activation and Inactivation of G Proteins
G-Protein Gated Ion Channels
Sensory organs,...
Adrenergic Receptors: β Subtype
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
Transducer Mechanism: Enzyme-Linked Receptors
Major types that are helpful drug targets include:

