QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: jpet.104.081562v1 313/3/1101    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Matsuura, B. Articles by Miller, L. J. Search for Related Content PubMed PubMed Citation Articles by Matsuura, B. Articles by Miller, L. J.

GASTROINTESTINAL, HEPATIC, PULMONARY, AND RENAL

Demonstration of a Specific Site of Covalent Labeling of the Human Motilin Receptor Using a Biologically Active Photolabile Motilin Analog

Cancer Center and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic in Scottsdale, Scottsdale, Arizona

The motilin receptor belongs to a group of class I G protein-coupled receptors that also includes the growth hormone secretagogue and ghrelin receptors. These represent clinically useful targets for pharmacotherapy. Their potentially unique structures and the molecular basis of their binding are not yet clear. We previously reported the initial affinity labeling of a region within this receptor (a cyanogen bromide fragment extending from the first to the second extracellular loop) using a position 1 photolabile motilin analog. To extend our understanding of the molecular basis of motilin binding, we have developed an additional radioiodinatable motilin analog probe having site of covalent attachment in position 5. This was a full agonist that bound to the motilin receptor specifically and with high affinity, and that efficiently established a single covalent bond to its receptor. Sequential chemical and enzymatic cleavage of labeled wild-type and mutant motilin receptor constructs established that the region of labeling was within the third extracellular loop. This was further localized to Phe³³² using radiochemical Edman degradation sequencing. These data provide the first spatial approximation constraint that can be used in the docking of this peptide ligand to its receptor. We hope that a series of such constraints can be determined to provide adequate structural information to begin to elucidate the conformation of this agonist-bound receptor and to ultimately be useful in the rational design of drugs acting at this important target.

Address correspondence to: Dr. Laurence J. Miller, Director, Cancer Center, Mayo Clinic in Scottsdale, 13400 East Shea Boulevard, Scottsdale, AZ 85259. E-mail: miller{at}mayo.edu

This article has been cited by other articles:

				H. Tokunaga, B. Matsuura, M. Dong, L. J. Miller, T. Ueda, S. Furukawa, Y. Hiasa, and M. Onji Mutational analysis of predicted intracellular loop domains of human motilin receptor Am J Physiol Gastrointest Liver Physiol, February 1, 2008; 294(2): G460 - G466. [Abstract] [Full Text] [PDF]

				B. Matsuura, M. Dong, S. Naik, L. J. Miller, and M. Onji Differential Contributions of Motilin Receptor Extracellular Domains for Peptide and Non-peptidyl Agonist Binding and Activity J. Biol. Chem., May 5, 2006; 281(18): 12390 - 12396. [Abstract] [Full Text] [PDF]