Document Detail

Distinct roles of the second and third cytoplasmic loops of bovine rhodopsin in G protein activation.
MedLine Citation:
PMID:  10930404     Owner:  NLM     Status:  MEDLINE    
In contrast to the extensive studies of light-induced conformational changes in rhodopsin, the cytoplasmic architecture of rhodopsin related to the G protein activation and the selective recognition of G protein subtype is still unclear. Here, we prepared a set of bovine rhodopsin mutants whose cytoplasmic loops were replaced by those of other ligand-binding receptors, and we compared their ability for G protein activation in order to obtain a clue to the roles of the second and third cytoplasmic loops of rhodopsin. The mutants bearing the third loop of four other G(o)-coupled receptors belonging to the rhodopsin superfamily showed significant G(o) activation, indicating that the third loop of rhodopsin possibly has a putative site(s) related to the interaction of G protein and that it is simply exchangeable with those of other G(o)-coupled receptors. The mutants bearing the second loop of other receptors, however, had little ability for G protein activation, suggesting that the second loop of rhodopsin contains a specific region essential for rhodopsin to be a G protein-activating form. Systematic chimeric and point mutational studies indicate that three amino acids (Glu(134), Val(138), and Cys(140)) in the N-terminal region of the second loop of rhodopsin are crucial for efficient G protein activation. These results suggest that the second and third cytoplasmic loops of bovine rhodopsin have distinct roles in G protein activation and subtype specificity.
T Yamashita; A Terakita; Y Shichida
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  275     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2000 Nov 
Date Detail:
Created Date:  2000-11-20     Completed Date:  2000-12-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  34272-9     Citation Subset:  IM    
Department of Biophysics, Graduate School of Science, Kyoto University, Japan.
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MeSH Terms
Amino Acid Sequence
Cytoplasm / metabolism*
Molecular Sequence Data
Mutagenesis, Site-Directed
Protein Binding
Protein Conformation
Rhodopsin / chemistry,  genetics,  metabolism*
Sequence Homology, Amino Acid
Reg. No./Substance:

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