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CRYSTAL STRUCTURE OF THE CONSTITUTIVELY ACTIVE E113Q,D2C,D282C RHODOPSIN MUTANT WITH BOUND GALPHACT PEPTIDE.CRYSTAL STRUCTURE OF THE CONSTITUTIVELY ACTIVE E113Q,D2C,D282C RHODOPSIN MUTANT WITH BOUND GALPHACT PEPTIDE.
Structural highlights
FunctionOPSD_BOVIN Photoreceptor required for image-forming vision at low light intensity. Required for photoreceptor cell viability after birth. Light-induced isomerization of 11-cis to all-trans retinal triggers a conformational change leading to G-protein activation and release of all-trans retinal (By similarity).[1] [2] Publication Abstract from PubMedG-protein-coupled receptors (GPCRs) comprise the largest family of membrane proteins in the human genome and mediate cellular responses to an extensive array of hormones, neurotransmitters and sensory stimuli. Although some crystal structures have been determined for GPCRs, most are for modified forms, showing little basal activity, and are bound to inverse agonists or antagonists. Consequently, these structures correspond to receptors in their inactive states. The visual pigment rhodopsin is the only GPCR for which structures exist that are thought to be in the active state. However, these structures are for the apoprotein, or opsin, form that does not contain the agonist all-trans retinal. Here we present a crystal structure at a resolution of 3 A for the constitutively active rhodopsin mutant Glu 113 Gln in complex with a peptide derived from the carboxy terminus of the alpha-subunit of the G protein transducin. The protein is in an active conformation that retains retinal in the binding pocket after photoactivation. Comparison with the structure of ground-state rhodopsin suggests how translocation of the retinal beta-ionone ring leads to a rotation of transmembrane helix 6, which is the critical conformational change on activation. A key feature of this conformational change is a reorganization of water-mediated hydrogen-bond networks between the retinal-binding pocket and three of the most conserved GPCR sequence motifs. We thus show how an agonist ligand can activate its GPCR. The structural basis of agonist-induced activation in constitutively active rhodopsin.,Standfuss J, Edwards PC, D'Antona A, Fransen M, Xie G, Oprian DD, Schertler GF Nature. 2011 Mar 31;471(7340):656-60. Epub 2011 Mar 9. PMID:21389983[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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