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

This Article Full Text Full Text (PDF) 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 Google Scholar Google Scholar Articles by Sugasawa, T. Articles by Strosberg, A. D. Search for Related Content PubMed PubMed Citation Articles by Sugasawa, T. Articles by Strosberg, A. D. Social Bookmarking                      What's this?

Volume 272, Number 34, Issue of August 22, 1997 pp. 21244-21252
©1997 by The American Society for Biochemistry and Molecular Biology, Inc.

Characterization of a Novel Iodocyanopindolol and SM-11044 Binding Protein, Which May Mediate Relaxation of Depolarized Rat Colon Tonus

(Received for publication, September 5, 1996, and in revised form, June 19, 1997)

Toshinari Sugasawa , Masago Matsuzaki-Fujita , Jean-Luc Guillaume , Luc Camoin , Shigeaki Morooka and A. Donny Strosberg

From the Institut Cochin de Génétique Moléculaire, CNRS-UPR 0415 and Université Paris VII, 22 rue Méchain, 75014 Paris, France and  Sumitomo Pharmaceuticals Co., Ltd., Research Center, 1-98, Kasugade-Naka 3-chome, Konohana-ku, Osaka 554, Japan

Studies under blockade of -, 1-, and 2-adrenoreceptors revealed a good correlation between the responses of rat colon relaxation of depolarized tonus and of rat adipocyte lipolysis elicited by catecholamines or BRL-37344, a selective 3-adrenoreceptor agonist, suggesting 3-adrenoreceptor stimulation. In contrast, SM-11044, a nonselective -adrenoreceptor agonist, stimulated colon relaxation more efficiently than lipolysis; its effects were differently antagonized by cyanopindolol with pA₂ values of 8.31 in colon and of 7.32 in adipocytes. Binding studies in rat colon smooth muscle membranes using [¹²⁵I]iodocyanopindolol under blockade of adrenaline and serotonin receptors revealed the existence of a single class of sites (K_d = 11.0 nM, B_max = 716.7 fmol/mg protein). The specific binding was saturable and reversible and was displaced by SM-11044 but not by BRL-37344, isoproterenol, noradrenaline, adrenaline, serotonin, nor dopamine. This binding site was photoaffinity labeled using [¹²⁵I]iodocyanopindolol-diazirine. The labeling was prevented by SM-11044 but not by BRL-37344.

The amino-terminal amino acid sequences of the high performance liquid chromatography-purified peptides generated by enzymatic and chemical cleavages of the affinity labeled 34-kDa protein confirmed that the novel iodocyanopindolol or SM-11044 binding protein of rat colon smooth muscle membranes is different from known adrenaline, serotonin, or dopamine receptors. Its functional role might include the relaxation of depolarized colon.

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