Selective Activation of Inhibitory G-Protein .alpha.-Subunits by Partial Agonists of the Human 5-HT1A Receptor

Plasma membranes from Chinese hamster ovary (CHO) cells transfected with the serotonin 5-HT1A receptor have been incubated with full or partial receptor agonists and the photoreactive GTP analog, 4-azidoanilido-[alpha-32P]-GTP ([32P]-AA-GTP), to characterize the resulting receptor-G-protein interact...

Full description

Saved in:
Bibliographic Details
Published in:Biochemistry (Easton) 1994-04, Vol.33 (14), p.4283-4290
Main Authors: Gettys, Thomas W, Fields, Timothy A, Raymond, John R
Format: Article
Language:English
Subjects:
Adenylyl Cyclase Inhibitors
Affinity Labels
Animals
Azides
Biological and medical sciences
CHO Cells
Cricetinae
GTP-Binding Proteins - metabolism
Guanosine Triphosphate - analogs & derivatives
HeLa Cells
Humans
Medical sciences
Neuropharmacology
Neurotransmitters. Neurotransmission. Receptors
Peptide Fragments - metabolism
Pharmacology. Drug treatments
Phosphorus Radioisotopes
Precipitin Tests
Pyrimidines - pharmacology
Serotonin Receptor Agonists - pharmacology
Serotoninergic system
Yohimbine - pharmacology
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Plasma membranes from Chinese hamster ovary (CHO) cells transfected with the serotonin 5-HT1A receptor have been incubated with full or partial receptor agonists and the photoreactive GTP analog, 4-azidoanilido-[alpha-32P]-GTP ([32P]-AA-GTP), to characterize the resulting receptor-G-protein interactions. Subsequent solubilization and immunoprecipitation of the membranes with anti-G(i)alpha-2 or anti-G(i)alpha-3 immunoglobulins revealed that full and partial agonists produce concentration-dependent labeling of the respective G-proteins with [32P]-AA-GTP. Full agonists of the 5-HT1A receptor [serotonin 5-hydroxytryptamine (5-HT) and 8-hydroxy-2-(di-n-propylamino)tetraline (8-OH-DPAT)] produced a 7-12-fold increase in the labeling of G(i)alpha-2 and G(i)alpha-3, whereas partial agonists (rauwolscine and ipsapirone) produced a smaller incorporation (2-5-fold) of [32P]-AA-GTP by the same G-proteins. The concentration of agonist producing half-maximal binding of [32P]-AA-GTP by G(i)alpha-3 [5-HT, 48 +/- 1 nM; 8-OH-DPAT, 28 +/- 1 nM; ipsapirone, 22 +/- 6 nM] compared to G(i)alpha-2 [5-HT, 124 +/- 38 nM; 8-OH-DPAT, 40 +/- 1 nM, ipsapirone, 82 +/- 7 nM] was lower with all agonists except rauwolscine, where the EC50's were similar (G(i)alpha-2, 604 +/- 145 nM; Gi alpha-3, 708 +/- 130 nM).
ISSN:0006-2960
1520-4995
DOI:10.1021/bi00180a024