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ID 26023
file
creator
Aizaki, Yoshimi
Maruyama, Kei
Nakano-Tetsuka, Mitsue
subject
G protein-coupled receptor
DRY motif
Melanin-concentrating hormone
Calcium influx
Site-directed mutagenesis
Constitutive activation
NDC
Biology
abstract
Rhodopsin family (class A) G protein-coupled receptors possess common key residues or motifs that appear to be important for receptor function. To clarify the roles of the highly conserved amino acid triplet Asp3.49-Arg3.50-Tyr3.51 (DRY motif), we examined how single-substitution mutations of the amino acids in the motif influenced specific features of rat melanin-concentrating hormone receptor 1 (MCH1R) activity. Substitution of either Asp1403.49 or Tyr1423.51 to Ala resulted in nonfunctional receptors, despite the retention of apparent potencies for agonist binding. These loss-of-function phenotypes may be caused by the lack of stimulation for GDP-GTP exchange observed in GTPγS-binding assays. On the other hand, substitution of Arg1413.50 to Ala caused a 4-fold reduction in the agonist binding affinity and, concomitantly, a rightward shift of the dose-dependency curve for calcium mobilization and inhibition of cyclic AMP production. Although many experimental studies have suggested that the DRY motif is involved in maintaining the receptor in its ground state, none of the DRY motif substitutions to Ala in MCH1R led to constitutive activation, in terms of the basal signaling level for ERK1/2 activation or GTPγS binding. These data suggest that the major contribution of the DRY motif in MCH1R is to govern receptor conformation and G protein coupling/recognition.
journal title
Peptides
volume
Volume 30
issue
Issue 5
start page
974
end page
981
date of issued
2009-05
publisher
Elsevier Science Inc.
issn
0196-9781
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
author
rights
Copyright (c) 2009 Elsevier Inc.
relation url
department
Graduate School of Integrated Arts and Sciences