3AYN

Crystal structure of squid isorhodopsin

Summary for 3AYN

• Entry DOI: 10.2210/pdb3ayn/pdb
• Related: 2z73 3AYM
• Descriptor: Rhodopsin, RETINAL, PALMITIC ACID, ... (7 entities in total)
• Functional Keywords: transmembrane protein, photoreceptor, chromophore, glycoprotein, lipoprotein, gq-type g-protein, phosphorylation, membrane, signaling protein
• Biological source: Todarodes pacificus (Japanese flying squid)
• Cellular location: Membrane; Multi-pass membrane protein: P31356
• Total number of polymer chains: 2
• Total formula weight: 102262.13

Authors

Murakami, M.,Kouyama, T. (deposition date: 2011-05-09, release date: 2011-08-17, Last modification date: 2024-10-16)

Primary citation

Murakami, M.,Kouyama, T.
Crystallographic Analysis of the Primary Photochemical Reaction of Squid Rhodopsin
J.Mol.Biol., 413:615-627, 2011

PubMed Abstract: Visual signal transduction is initiated by the photoisomerization of 11-cis retinal upon rhodopsin ligation. Unlike vertebrate rhodopsin, which interacts with Gt-type G-protein to stimulate the cyclic GMP signaling pathway, invertebrate rhodopsin interacts with Gq-type G-protein to stimulate a signaling pathway that is based on inositol 1,4,5-triphosphate. Since the inositol 1,4,5-triphosphate signaling pathway is utilized by mammalian nonvisual pigments and a large number of G-protein-coupled receptors, it is important to elucidate how the activation mechanism of invertebrate rhodopsin differs from that of vertebrate rhodopsin. Previous crystallographic studies of squid and bovine rhodopsins have shown that there is a profound difference in the structures of the retinal-binding pockets of these photoreceptors. Here, we report the crystal structures of all-trans bathorhodopsin (Batho; the first photoreaction intermediate) and the artificial 9-cis isorhodopsin (Iso) of squid rhodopsin. Upon the formation of Batho, the central moiety of the retinal was observed to move largely towards the cytoplasmic side, while the Schiff base and the ionone ring underwent limited movements (i.e., the all-trans retinal in Batho took on a right-handed screwed configuration). Conversely, the 9-cis retinal in Iso took on a planar configuration. Our results suggest that the light energy absorbed by squid rhodopsin is mostly converted into the distortion energy of the retinal polyene chain and surrounding residues.

PubMed: 21906602
DOI: 10.1016/j.jmb.2011.08.044

Experimental method

X-RAY DIFFRACTION (2.7 Å)