Article Information

• PDF (388 kb)

PubMed

• Articles by U.C. Fischer
• Articles by D. Oesterhelt

Related Articles

• Activation of rhodopsin: new insights from structural and bi...

  Activation of rhodopsin: new insights from structural and biochemical studies Trends in Biochemical Sciences, Volume 26, Issue 5, 1 May 2001, Pages 318-324 Tetsuji Okada, Oliver P. Ernst, Krzysztof Palczewski and Klaus Peter Hofmann Abstract G-protein-coupled receptors (GPCRs) are involved in a vast variety of cellular signal transduction processes from visual, taste and odor perceptions to sensing the levels of many hormones and neurotransmitters. As a result of agonist-induced conformation changes, GPCRs become activated and catalyze nucleotide exchange within the G proteins, thus detecting and amplifying the signal. GPCRs share a common heptahelical transmembrane structure as well as many conserved key residues and regions. Rhodopsins are prototypical GPCRs that detect photons in retinal photoreceptor cells and trigger a phototransduction cascade that culminates in neuronal signaling. Biophysical and biochemical studies of rhodopsin activation, and the recent crystal structure determination of bovine rhodopsin, have provided new information that enables a more complete mechanism of vertebrate rhodopsin activation to be proposed. In many aspects, rhodopsin might provide a structural and functional template for other members of the GPCR family. Abstract | Full Text | PDF (341 kb)

• Visual Receptors

  Visual Receptors Biophysical Journal, Volume 94, Issue , 1 February 2008, Pages 791-796 Full Text | PDF (90 kb)

• Binding of Transducin and Transducin-Derived Peptides to Rho...

  Binding of Transducin and Transducin-Derived Peptides to Rhodopsin Studied by Attenuated Total Reflection–Fourier Transform Infrared Difference Spectroscopy Biophysical Journal, Volume 75, Issue 3, 1 September 1998, Pages 1306-1318 Karim Fahmy Abstract Fourier transform infrared difference spectroscopy combined with the attenuated total reflection technique allows the monitoring of the association of transducin with bovine photoreceptor membranes in the dark. Illumination causes infrared absorption changes linked to formation of the light-activated rhodopsin-transducin complex. In addition to the spectral changes normally associated with meta II formation, prominent absorption increases occur at 1735cm, 1640cm, 1550cm, and 1517cm. The DO sensitivity of the broad carbonyl stretching band around 1735cm indicates that a carboxylic acid group becomes protonated upon formation of the activated complex. Reconstitution of rhodopsin into phosphatidylcholine vesicles has little influence on the spectral properties of the rhodopsin-transducin complex, whereas pH affects the intensity of the carbonyl stretching band. A C-terminal peptide comprising amino acids 340–350 of the transducin -subunit reproduces the frequencies and isotope sensitivities of several of the transducin-induced bands between 1500 and 1800cm, whereas an N-terminal peptide (aa 8–23) does not. Therefore, the transducin-induced absorption changes can be ascribed mainly to an interaction between the transducin- C-terminus and rhodopsin. The 1735cm vibration is also seen in the complex with C-terminal peptides devoid of free carboxylic acid groups, indicating that the corresponding carbonyl group is located on rhodopsin. Abstract | Full Text | PDF (236 kb)

• …more

Abstract

Protonation changes of the protein occur during the reconstitution of bacteriorhodopsin from bacterio-opsin and all-trans retinal in the purple membrane of Halobacterium halobium. The protonation changes are conveniently determined from measures of the pH changes after photoisomerisation of 9-cis retinal in apomembrane preparations, which induces the reconstitution. In addition, to the omega-amino group of the lysine which is involved in the condensation of retinal and bacterio-opsin, the dissociation equilibria of at least two other amino acid residues are changed during the reconstitution. The results are consistent with a proposed model of chromophore structure in which an interaction of the Schiff's base occurs with two protonable amino acid residues.