HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 281, Issue 26, 18120-18125, June 30, 2006

This Article Full Text Full Text (PDF) All Versions of this Article: 281/26/18120    most recent M601791200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Behr, B. Articles by Klotz, K.-N. Search for Related Content PubMed PubMed Citation Articles by Behr, B. Articles by Klotz, K.-N. Social Bookmarking                      What's this?

Novel Mutants of the Human ₁-Adrenergic Receptor Reveal Amino Acids Relevant for Receptor Activation^*

Björn Behr¹, Carsten Hoffmann¹, Gianluca Ottolina, and Karl-Norbert Klotz²

From the Institut für Pharmakologie und Toxikologie, Universität Würzburg, D-97078 Würzburg, Germany and Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, I-20131 Milan, Italy

Activation of G protein-coupled receptors like the ₁-adrenergic receptor results in conformational changes that ultimately lead to signal propagation through a G protein to an effector like adenylyl cyclase. In this study we identified amino acids that seem to be critical for activation of the human ₁-adrenergic receptor. Activation patterns of mutant receptors were analyzed using two structurally different ligands for -adrenergic receptors that both are mixed agonist/antagonists. Broxaterol and terbutaline are agonists at ₂- and ₃-receptors; however, they act as antagonists at the ₁-subtype. We reasoned that this functional selectivity may be reflected by a corresponding sequence pattern in the receptor subtypes. Therefore, we exchanged single amino acids of the ₁-adrenergic receptor for residues that were identical in the ₂- and ₃-subtypes but different in the ₁-receptor. Pharmacological characterization of such receptor mutants revealed that binding of a panel of agonists and antagonists including broxaterol and terbutaline was unaltered. However, two of the mutants (I185V and D212N) were activated by broxaterol and terbutaline, which acted as antagonists at the wild-type receptor. Two additional mutants (V120L and K253R) could be activated by terbutaline alone, which is structurally more closely related to endogenous catecholamines like epinephrine than to broxaterol. A model of the human ₁-adrenergic receptor showed that the four gain-of-function mutations are outside of the putative ligand-binding domain substantiating the lack of an effect of the mutations on binding characteristics. These results support the notion that Val-120, Ile-185, Asp-212, and Lys-253 are critically involved in conformational changes occurring during receptor activation.

Received for publication, February 24, 2006 , and in revised form, April 7, 2006.

^* This work was supported by the Vigoni program (to K.-N. K.) to foster German-Italian collaborations. 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.

¹ Both authors contributed equally to this work.

² To whom correspondence should be addressed: Inst. für Pharmakologie und Toxikologie, Universität Würzburg, Versbacher Str. 9, D-97078 Würzburg, Germany. Tel.: 49-931-201-48405; Fax 49-931-201-48539; E-mail: klotz{at}toxi.uni-wuerzburg.de.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				B. Holst, J. Mokrosinski, M. Lang, E. Brandt, R. Nygaard, T. M. Frimurer, A. G. Beck-Sickinger, and T. W. Schwartz Identification of an Efficacy Switch Region in the Ghrelin Receptor Responsible for Interchange between Agonism and Inverse Agonism J. Biol. Chem., May 25, 2007; 282(21): 15799 - 15811. [Abstract] [Full Text] [PDF]