Arrangement of rhodopsin transmembrane α-helices

Rhodopsins, the photoreceptors in rod cells, are G-protein-coupled receptors with seven hydrophobic segments containing characteristic conserved sequence patterns that define a large family,. Members of the family are expected to share a conserved transmembrane structure. Direct evidence for the arr...

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Bibliographic Details
Published in:Nature (London) 1997-09, Vol.389 (6647), p.203-206
Main Authors: Schertler, Gebhard F. X, Unger, Vinzenz M, Hargrave, Paul A, Baldwin, Joyce M
Format: Article
Language:English
Subjects:
Amphibians
Analytical, structural and metabolic biochemistry
Animals
Anura
Biological and medical sciences
Cattle
Cellular biology
Crystallography
Crystals
Freshwater
Fundamental and applied biological sciences. Psychology
Humanities and Social Sciences
letter
Membranes
multidisciplinary
Non metallic chromoproteins, photoproteins
Protein Conformation
Proteins
Reptiles & amphibians
Rhodopsin - chemistry
Rhodopsin - ultrastructure
Science
Science (multidisciplinary)
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Summary:Rhodopsins, the photoreceptors in rod cells, are G-protein-coupled receptors with seven hydrophobic segments containing characteristic conserved sequence patterns that define a large family,. Members of the family are expected to share a conserved transmembrane structure. Direct evidence for the arrangement of seven α-helices was obtained from a 9å projection map of bovine rhodopsin. Structural constraints inferred from a comparison of G-protein-coupled receptor sequences were used to assign the seven hydrophobic stretches in the sequence to features in the projection map. A low-resolution three-dimensional structure of bovine rhodopsin and two projection structures of frog rhodopsin confirmed the position of the three least tilted helices, 4, 6 and 7. A more elongated peak of density for helix 5 indicated that it is tilted or bent,, but helices 1, 2 and 3 were not resolved. Here we have used electron micrographs of frozen-hydrated two-dimensional frog rhodopsin crystals to determine the structure of frog rhodopsin. Seven rods of density in the map are used to estimate tilt angles for the seven helices. Density visible on the extracellular side of the membrane suggests a folded domain. Density extends from helix 6 on the intracellular side, and a short connection between helices 1 and 2, and possibly a part of the carboxy terminus, are visible.
ISSN:0028-0836
1476-4687
DOI:10.1038/38316