title: Movement of retinal along the visual transduction path.
abstract: Movement of the ligand/receptor complex in rhodopsin (Rh) has been traced. Bleaching of diazoketo rhodopsin (DK-Rh) containing 11-cis-3-diazo-4-oxo-retinal yields batho-, lumi-, meta-I-, and meta-II-Rh intermediates corresponding to those of native Rh but at lower temperatures. Photoaffinity labeling of DK-Rh and these bleaching intermediates shows that the ionone ring cross-links to tryptophan-265 on helix F in DK-Rh and batho-Rh, and to alanine-169 on helix D in lumi-, meta-I-, and meta-II-Rh intermediates. It is likely that these movements involving a flip-over of the chromophoric ring trigger changes in cytoplasmic membrane loops resulting in heterotrimeric guanine nucleotide-binding protein (G protein) activation.
authors.affiliation: Department of Chemistry, Columbia University, New York, NY 10027, USA.
authors.forename: B
authors.initials: B
authors.lastname: Borhan
authors.forename: M L
authors.initials: ML
authors.lastname: Souto
authors.forename: H
authors.initials: H
authors.lastname: Imai
authors.forename: Y
authors.initials: Y
authors.lastname: Shichida
authors.forename: K
authors.initials: K
authors.lastname: Nakanishi
mesh_terms: D000345:Affinity Labels; D001391:Azo Compounds / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002942:Circular Dichroism; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism; D008024:Ligands; D008027:Light; D008958:Models, Molecular; D010782:Photolysis; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012172:Retinaldehyde / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D012243:Rhodopsin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000378:metabolism*; D013237:Stereoisomerism; D013696:Temperature; D014785:Vision, Ocular
chemical_list: D000345:Affinity Labels; D001391:Azo Compounds; D008024:Ligands; D012243:Rhodopsin; D020962:Heterotrimeric GTP-Binding Proteins; D012172:Retinaldehyde