Document Detail


The Active Site of Melanopsin: The Biological Clock Photoreceptor.
MedLine Citation:
PMID:  23145979     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The non-visual ocular photoreceptor melanopsin, found in the neurons of vertebrate inner retina, absorbs blue light and triggers the 'biological clock' of mammals by activating the suprachiasmatic nuclei (a small region of the brain that regulates the circadian rhythms of neuronal and hormonal activities over 24-hour cycles). The structure of melanopsin, however, has yet to be established. Here, we propose for the first time a structural model of the active site of mouse melanopsin. The homology model is based on the crystal structure of squid rhodopsin (λmax = 490 nm) and shows a maximal absorbance (λmax = 447 nm), consistent with the ob-served absorption of the photoreceptor. The 43 nm spectral shift is due to an increased bond-length alternation of the 11-cis-retinal chromophore, induced by the N87Q mutation and the water-mediated hydrogen-bonding interactions with the Schiff base linkage. These findings, analogous to spectral changes observed in the G89Q bovine rhodopsin mutant, sug-gest that single site mutations can convert photopigments into visual light-sensors or non-visual sensory photoreceptors.
Authors:
Sivakumar Sekharan; Jennifer N Wei; Victor Salvador Batista
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-12
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  -     ISSN:  1520-5126     ISO Abbreviation:  J. Am. Chem. Soc.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-13     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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