Publication Date:
1991-02-01
Description:
Rhodopsin and the visual pigments are a distinct group within the family of G-protein-linked receptors in that they have a covalently bound ligand, the 11-cis-retinal chromophore, whereas all of the other receptors bind their agonists through noncovalent interactions. The retinal chromophore in rhodopsin is bound by means of a protonated Schiff base linkage to the epsilon-amino group of Lys-296. Two rhodopsin mutants have been constructed, K296G and K296A, in which the covalent linkage to the chromophore is removed. Both mutants form a pigment with an absorption spectrum close to that of the wild type when reconstituted with the Schiff base of an n-alkylamine and 11-cis-retinal. In addition, the pigment formed from K296G and the n-propylamine Schiff base of 11-cis-retinal was found to activate transducin in a light-dependent manner, with 30 to 40% of the specific activity measured for the wild-type protein. It appears that the covalent bond is not essential for binding of the chromophore or for catalytic activation of transducin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zhukovsky, E A -- Robinson, P R -- Oprian, D D -- 5T32 GM07596-11/GM/NIGMS NIH HHS/ -- EY07965/EY/NEI NIH HHS/ -- R01 EY007965/EY/NEI NIH HHS/ -- S07 RR07044/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1991 Feb 1;251(4993):558-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate Department of Biochemistry, Brandeis University, Waltham, MA 02254.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1990431" target="_blank"〉PubMed〈/a〉
Keywords:
Binding Sites
;
Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
;
Kinetics
;
Mutagenesis, Site-Directed
;
Protein Binding
;
Retinaldehyde/*metabolism
;
Rhodopsin/genetics/*metabolism/radiation effects
;
Schiff Bases
;
Spectrophotometry
;
Transducin/*metabolism/radiation effects
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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