title: Requirement of rigid-body motion of transmembrane helices for light activation of rhodopsin.
abstract: Conformational changes are thought to underlie the activation of heterotrimeric GTP-binding protein (G protein)-coupled receptors. Such changes in rhodopsin were explored by construction of double cysteine mutants, each containing one cysteine at the cytoplasmic end of helix C and one cysteine at various positions in the cytoplasmic end of helix F. Magnetic dipolar interactions between spin labels attached to these residues revealed their proximity, and changes in their interaction upon rhodopsin light activation suggested a rigid body movement of helices relative to one another. Disulfide cross-linking of the helices prevented activation of transducin, which suggests the importance of this movement for activation of rhodopsin.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Farrens
authors.forename: C
authors.initials: C
authors.lastname: Altenbach
authors.forename: K
authors.initials: K
authors.lastname: Yang
authors.forename: W L
authors.initials: WL
authors.lastname: Hubbell
authors.forename: H G
authors.initials: HG
authors.lastname: Khorana
mesh_terms: D000595:Amino Acid Sequence; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D005136:Eye Proteins; D051606:G-Protein-Coupled Receptor Kinase 1; D008027:Light; D008969:Molecular Sequence Data; D009154:Mutation; D010084:Oxidation-Reduction; D010618:Phenanthrolines; D011494:Protein Kinases / Q000378:metabolism; D017433:Protein Structure, Secondary; D012243:Rhodopsin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D013113:Spin Labels; D015293:Transducin / Q000378:metabolism
chemical_list: D004220:Disulfides; D005136:Eye Proteins; D010618:Phenanthrolines; D013113:Spin Labels; D012243:Rhodopsin; D011494:Protein Kinases; D051606:G-Protein-Coupled Receptor Kinase 1; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D015293:Transducin; D003545:Cysteine; C025205:1,10-phenanthroline