title: Requirement of GTP hydrolysis for dissociation of the signal recognition particle from its receptor.
abstract: The signal recognition particle (SRP) directs signal sequence specific targeting of ribosomes to the rough endoplasmic reticulum. Displacement of the SRP from the signal sequence of a nascent polypeptide is a guanosine triphosphate (GTP)-dependent reaction mediated by the membrane-bound SRP receptor. A nonhydrolyzable GTP analog can replace GTP in the signal sequence displacement reaction, but the SRP then fails to dissociate from the membrane. Complexes of the SRP with its receptor containing the nonhydrolyzable analog are incompetent for subsequent rounds of protein translocation. Thus, vectorial targeting of ribosomes to the endoplasmic reticulum is controlled by a GTP hydrolysis cycle that regulates the affinity between the SRP, signal sequences, and the SRP receptor.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, Worcester 01655.
authors.forename: T
authors.initials: T
authors.lastname: Connolly
authors.forename: P J
authors.initials: PJ
authors.lastname: Rapiejko
authors.forename: R
authors.initials: R
authors.lastname: Gilmore
mesh_terms: D000818:Animals; D002499:Centrifugation, Density Gradient; D004721:Endoplasmic Reticulum / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006868:Hydrolysis; D007700:Kinetics; D046911:Macromolecular Substances; D011485:Protein Binding; D014176:Protein Biosynthesis; D011956:Receptors, Cell Surface / Q000302:isolation & purification / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; D012261:Ribonucleoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism; D018271:Signal Recognition Particle; D014158:Transcription, Genetic; D014721:Vesicular stomatitis Indiana virus / Q000235:genetics / Q000378:metabolism
chemical_list: D046911:Macromolecular Substances; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; D012261:Ribonucleoproteins; D018271:Signal Recognition Particle; C036318:signal peptide receptor; D006165:Guanylyl Imidodiphosphate; D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins