3PQR

Crystal structure of Metarhodopsin II in complex with a C-terminal peptide derived from the Galpha subunit of transducin

3PQR の概要

• エントリーDOI: 10.2210/pdb3pqr/pdb
• 関連するPDBエントリー: 3PXO
• 関連するBIRD辞書のPRD_ID: PRD_900006
• 分子名称: Rhodopsin, ACETATE ION, Guanine nucleotide-binding protein G(t) subunit alpha-1, ... (11 entities in total)
• 機能のキーワード: protein, retinal protein, photoreceptor, active state, chromophore, g-protein coupled receptor, glycoprotein, lipoprotein, palmitate, phosphoprotein, photoreceptor protein, sensory transduction, transducer, transmembrane, vision, signaling protein, g-protein, transducin, galpha subunit, membrane, receptor, gtp-binding, myristate, nucleotide-binding, g-protein-coupled receptor, rhodopsin, opsin
• 由来する生物種: Bos taurus (bovine); 詳細
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 42944.88

構造登録者

Choe, H.-W.,Kim, Y.J.,Park, J.H.,Morizumi, T.,Pai, E.F.,Krauss, N.,Hofmann, K.P.,Scheerer, P.,Ernst, O.P. (登録日: 2010-11-26, 公開日: 2011-03-09, 最終更新日: 2024-10-30)

主引用文献

Choe, H.W.,Kim, Y.J.,Park, J.H.,Morizumi, T.,Pai, E.F.,Krauss, N.,Hofmann, K.P.,Scheerer, P.,Ernst, O.P.
Crystal structure of metarhodopsin II.
Nature, 471:651-655, 2011

PubMed Abstract: G-protein-coupled receptors (GPCRs) are seven transmembrane helix (TM) proteins that transduce signals into living cells by binding extracellular ligands and coupling to intracellular heterotrimeric G proteins (Gαβγ). The photoreceptor rhodopsin couples to transducin and bears its ligand 11-cis-retinal covalently bound via a protonated Schiff base to the opsin apoprotein. Absorption of a photon causes retinal cis/trans isomerization and generates the agonist all-trans-retinal in situ. After early photoproducts, the active G-protein-binding intermediate metarhodopsin II (Meta II) is formed, in which the retinal Schiff base is still intact but deprotonated. Dissociation of the proton from the Schiff base breaks a major constraint in the protein and enables further activating steps, including an outward tilt of TM6 and formation of a large cytoplasmic crevice for uptake of the interacting C terminus of the Gα subunit. Owing to Schiff base hydrolysis, Meta II is short-lived and notoriously difficult to crystallize. We therefore soaked opsin crystals with all-trans-retinal to form Meta II, presuming that the crystal's high concentration of opsin in an active conformation (Ops*) may facilitate all-trans-retinal uptake and Schiff base formation. Here we present the 3.0 Å and 2.85 Å crystal structures, respectively, of Meta II alone or in complex with an 11-amino-acid C-terminal fragment derived from Gα (GαCT2). GαCT2 binds in a large crevice at the cytoplasmic side, akin to the binding of a similar Gα-derived peptide to Ops* (ref. 7). In the Meta II structures, the electron density from the retinal ligand seamlessly continues into the Lys 296 side chain, reflecting proper formation of the Schiff base linkage. The retinal is in a relaxed conformation and almost undistorted compared with pure crystalline all-trans-retinal. By comparison with early photoproducts we propose how retinal translocation and rotation induce the gross conformational changes characteristic for Meta II. The structures can now serve as models for the large GPCR family.

PubMed: 21389988
DOI: 10.1038/nature09789

実験手法

X-RAY DIFFRACTION (2.85 Å)