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The G alpha q and G alpha 11 proteins couple the thyrotropin-releasing hormone receptor to phospholipase C in GH3 rat pituitary cells

Aragay, Anna M. and Katz, Arieh and Simon, Melvin I. (1992) The G alpha q and G alpha 11 proteins couple the thyrotropin-releasing hormone receptor to phospholipase C in GH3 rat pituitary cells. Journal of Biological Chemistry, 267 (35). pp. 24983-24988. ISSN 0021-9258. http://resolver.caltech.edu/CaltechAUTHORS:ARAjbc92

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Abstract

Thyrotropin-releasing hormone stimulates the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) in GH3 cell membranes. The stimulation of the phosphoinositide phospholipase C (PI/PLC) activity can be blocked by incubation of GH3 membranes with polyclonal antibodies directed against a peptide derived from the C-terminal region of G alpha q and G alpha 11. Antibodies directed against the C- terminal region of other G alpha-subunits had no detectable effect. The inhibition was specific since addition of the peptide that was used to prepare the antibody completely reversed the inhibition. Further evidence for the coupling of the TRH receptor to G alpha q or G alpha 11 comes from a reconstitution experiment in which human embryonic kidney cells were transiently transfected with cDNAs corresponding to the TRH receptor, G alpha q or G alpha 11. The PIP2 hydrolysis detected with membranes from cells that over-expressed the TRH receptor alone was low, however, co-expression with the G alpha q or G alpha 11 subunits produced a synergistic stimulation of PI-PLC activity. In contrast, co-expression of these alpha-subunits with the M2 muscarinic acetylcholine receptor induced a weak stimulation of PIP2 hydrolysis. The results presented here suggest that the TRH-dependent stimulation of PI-PLC in GH3 cells is mediated through the G-protein alpha- subunits, G alpha q and/or G alpha 11.


Item Type:Article
Additional Information:Copyright © 1992 by the American Society for Biochemistry and Molecular Biology. (Received for publication, August 10, 1992) We thank Dr. J. Watson for technical assistance in the preparation of the antibodies. We are also grateful to Dr. T. Wilkie, Dr. J. Watson, and V. Manzino for the critical reading of this manuscript. We thank Dr. Gershengorn for providing us with the TRH receptor clone. This work was supported by Grant GM 34236 from the National Institutes of Health. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Record Number:CaltechAUTHORS:ARAjbc92
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:ARAjbc92
Alternative URL:http://www.jbc.org/cgi/content/abstract/267/35/24983
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ID Code:6851
Collection:CaltechAUTHORS
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Deposited On:27 Dec 2006
Last Modified:26 Dec 2012 09:25

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