Visual pigment: G-protein-coupled receptor for light signals.

Abstract

The visual pigment present in photoreceptor cells is a prototypical G-protein-coupled receptor (GPCR) that receives a light signal from the outer environment using a light-absorbing chromophore, 11-cis-retinal. Through cis-trans isomerization of the chromophore, light energy is transduced into chemical free energy, which is in turn utilized for conformational changes in the protein to activate the retinal G-protein. In combination with site-directed mutagenesis, various spectroscopic and biochemical studies identified functional residues responsible for chromophore binding, color regulation, intramolecular signal transduction and G-protein coupling. Extensive studies reveal that these residues are localized into specific domains of visual pigments, suggesting a highly manipulated molecular architecture in visual pigments. In addition to the recent findings on dysfunctional mutations in patients with retinitis pigmentosa or congenital night blindness, the mechanism of intramolecular signal transduction in visual pigments and their evolutionary relationship are discussed.

• Authors: Y Shichida, H Imai
• Journal: Cellular and molecular life sciences : CMLS (Cell Mol Life Sci) Vol. 54 Issue 12 Pg. 1299-315 (Dec 1998) ISSN: 1420-682X [Print] Switzerland
• PMID: 9893707 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Review)

Chemical References

• Receptors, Cell Surface
• Retinal Pigments
• GTP-Binding Proteins

Topics

• Amino Acid Sequence
• Animals
• Color Perception (physiology)
• Evolution, Molecular
• GTP-Binding Proteins (physiology)
• Humans
• Light
• Molecular Sequence Data
• Photoreceptor Cells (physiology)
• Receptors, Cell Surface (chemistry, physiology)
• Retinal Pigments (chemistry, physiology)
• Signal Transduction