Internalization and homologous desensitization of the GLP-1 receptor depend on phosphorylation of the receptor carboxyl tail at the same three sites.

Details

Serval ID
serval:BIB_711D5C683DB1
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Internalization and homologous desensitization of the GLP-1 receptor depend on phosphorylation of the receptor carboxyl tail at the same three sites.
Journal
Molecular Endocrinology
Author(s)
Widmann C., Dolci W., Thorens B.
ISSN
0888-8809[print], 0888-8809[linking]
Publication state
Published
Issued date
07/1997
Volume
11
Number
8
Pages
1094-1102
Language
english
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov't
Publication Status: ppublish
Abstract
Homologous desensitization and internalization of the GLP-1 receptor correlate with phosphorylation of the receptor in a 33-amino acid segment of the cytoplasmic tail. Here, we identify the sites of phosphorylation as being three serine doublets located at positions 441/442, 444/445, and 451/452. The role of phosphorylation on homologous desensitization was assessed after stable expression in fibroblasts of the wild type or of mutant receptors in which phosphorylation sites were changed in various combinations to alanines. We showed that desensitization, as measured by a decrease in the maximal production of cAMP after a first exposure of the cells to GLP-1, was strictly dependent on phosphorylation. Furthermore, the number of phosphorylation sites correlated with the extent of desensitization with no, intermediate, or maximal desensitization observed in the presence of one, two, or three phosphorylation sites, respectively. Internalization of the receptor-ligand complex was assessed by measuring the rate of internalization of bound [125I]GLP-1 or the redistribution of the receptor to an endosomal compartment after agonist binding. Our data demonstrate that internalization was prevented in the absence of receptor phosphorylation and that intermediate rates of endocytosis were obtained with receptors containing one or two phosphorylation sites. Thus, homologous desensitization and internalization require phosphorylation of the receptor at the same three sites. However, the differential quantitative impairment of these two processes in the single and double mutants suggests different molecular mechanisms controlling desensitization and internalization.
Keywords
Amino Acid Sequence, Animals, Binding Sites, CHO Cells, COS Cells/metabolism, Cricetinae, Cyclic AMP/metabolism, Endocytosis, Fibroblasts/drug effects, Fibroblasts/metabolism, Glucagon-Like Peptide 1, Kinetics, Molecular Sequence Data, Peptides/metabolism, Peptides/pharmacology, Phosphorylation, Protein Kinase C/metabolism, Receptors, Glucagon/drug effects, Receptors, Glucagon/genetics, Recombinant Proteins/genetics, Recombinant Proteins/metabolism, Sequence Deletion, Serine/metabolism
Pubmed
Web of science
Open Access
Yes
Create date
24/01/2008 14:43
Last modification date
20/08/2019 14:29
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