2Z73

Crystal structure of squid rhodopsin

Summary for 2Z73

• Entry DOI: 10.2210/pdb2z73/pdb
• Descriptor: Rhodopsin, octyl beta-D-glucopyranoside, RETINAL, ... (8 entities in total)
• Functional Keywords: visual pigment, gq-type, g-protein coupled receptor, chromophore, glycoprotein, lipoprotein, membrane, palmitate, phosphorylation, photoreceptor protein, retinal protein, sensory transduction, transducer, transmembrane, vision, membrane 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: 103432.12

Authors

Murakami, M.,Kouyama, T. (deposition date: 2007-08-13, release date: 2008-05-13, Last modification date: 2024-10-16)

Primary citation

Murakami, M.,Kouyama, T.
Crystal structure of squid rhodopsin.
Nature, 453:363-367, 2008

PubMed Abstract: Invertebrate phototransduction uses an inositol-1,4,5-trisphosphate signalling cascade in which photoactivated rhodopsin stimulates a G(q)-type G protein, that is, a class of G protein that stimulates membrane-bound phospholipase Cbeta. The same cascade is used by many G-protein-coupled receptors, indicating that invertebrate rhodopsin is a prototypical member. Here we report the crystal structure of squid (Todarodes pacificus) rhodopsin at 2.5 A resolution. Among seven transmembrane alpha-helices, helices V and VI extend into the cytoplasmic medium and, together with two cytoplasmic helices, they form a rigid protrusion from the membrane surface. This peculiar structure, which is not seen in bovine rhodopsin, seems to be crucial for the recognition of G(q)-type G proteins. The retinal Schiff base forms a hydrogen bond to Asn 87 or Tyr 111; it is far from the putative counterion Glu 180. In the crystal, a tight association is formed between the amino-terminal polypeptides of neighbouring monomers; this intermembrane dimerization may be responsible for the organization of hexagonally packed microvillar membranes in the photoreceptor rhabdom.

PubMed: 18480818
DOI: 10.1038/nature06925

Experimental method

X-RAY DIFFRACTION (2.5 Å)