Crystal structure of rhodopsin: implications for vision and beyond

Curr Opin Struct Biol. 2001 Aug;11(4):420-6. doi: 10.1016/s0959-440x(00)00227-x.


A heptahelical transmembrane bundle is a common structural feature of G-protein-coupled receptors (GPCRs) and bacterial retinal-binding proteins, two functionally distinct groups of membrane proteins. Rhodopsin, a photoreceptor protein involved in photopic (rod) vision, is a prototypical GPCR that contains 11-cis-retinal as its intrinsic chromophore ligand. Therefore, uniquely, rhodopsin is a GPCR and also a retinal-binding protein, but is not found in bacteria. Rhodopsin functions as a typical GPCR in processes that are triggered by light and photoisomerization of its ligand. Bacteriorhodopsin is a light-driven proton pump with an all-trans-retinal chromophore that photoisomerizes to 13-cis-retinal. The recent crystal structure determination of bovine rhodopsin revealed a structure that is not similar to previously established bacteriorhodopsin structures. Both groups of proteins have a heptahelical transmembrane bundle structure, but the helices are arranged differently. The activation of rhodopsin involves rapid cis-trans photoisomerization of the chromophore, followed by slower and incompletely defined structural rearrangements. For rhodopsin and related receptors, a common mechanism is predicted for the formation of an active state intermediate that is capable of interacting with G proteins.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Animals
  • Bacteriorhodopsins / chemistry
  • Cattle
  • Crystallography, X-Ray
  • GTP-Binding Proteins / chemistry*
  • Isomerism
  • Ligands
  • Membrane Proteins / chemistry*
  • Membrane Proteins / physiology
  • Photoreceptor Cells, Vertebrate / chemistry*
  • Protein Conformation
  • Receptors, Cell Surface / chemistry
  • Receptors, Cell Surface / metabolism
  • Retinaldehyde / chemistry
  • Retinaldehyde / metabolism*
  • Rhodopsin / chemistry*
  • Rhodopsin / metabolism


  • Ligands
  • Membrane Proteins
  • Receptors, Cell Surface
  • Bacteriorhodopsins
  • Rhodopsin
  • GTP-Binding Proteins
  • Retinaldehyde