Publication Date:
1994-11-25
Description:
Light absorption by rhodopsin generates metarhodopsin, which activates heterotrimeric guanine nucleotide-binding proteins (G proteins) in photoreceptor cells of vertebrates and invertebrates. In contrast to vertebrate metarhodopsins, most invertebrate metarhodopsins are thermally stable and regenerate rhodopsin by absorption of a second photon. In experiments with Rh1 Drosophila rhodopsin, the thermal stability of metarhodopsin was found not to be an intrinsic property of the visual pigment but a consequence of its interaction with arrestin (49 kilodaltons). The stabilization of metarhodopsin resulted in a large decrease in the efficiency of G protein activation. Light absorption by thermally stable metarhodopsin initially regenerated an inactive rhodopsin-like intermediate, which was subsequently converted in the dark to active rhodopsin. The accumulation of inactive rhodopsin at higher light levels may represent a mechanism for gain regulation in the insect visual cycle.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kiselev, A -- Subramaniam, S -- New York, N.Y. -- Science. 1994 Nov 25;266(5189):1369-73.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973725" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Antigens/*metabolism
;
Arrestin
;
Darkness
;
Drosophila
;
Eye Proteins/*metabolism
;
GTP-Binding Proteins/*metabolism
;
*Light
;
Models, Biological
;
Phosphorylation
;
Photoreceptor Cells, Invertebrate/*metabolism
;
Rhodopsin/*analogs & derivatives/chemistry/*metabolism
;
Spectrophotometry, Ultraviolet
;
Temperature
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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