Elongation arrest is a physiologically important function of signal recognition particle.
Signal recognition particle (SRP) targets proteins for co-translational insertion through or into the endoplasmic reticulum membrane. Mammalian SRP slows nascent chain elongation by the ribosome during targeting in vitro. This 'elongation arrest' activity requires the SRP9/14 subunit of the particle and interactions of the C-terminus of SRP14. We have purified SRP from Saccharomyces cerevisiae and demonstrated that it too has elongation arrest activity. A yeast SRP containing Srp14p truncated at its C-terminus (delta C29) did not maintain elongation arrest, was substantially deficient in promoting translocation and interfered with targeting by wild-type SRP. In vivo, this mutation conferred a constitutive defect in the coupling of protein translation and translocation and temperature-sensitive growth, but only a slight defect in protein translocation. In combination, these data indicate that the primary defect in SRP delta C29 is in elongation arrest, and that this is a physiologically important and conserved function of eukaryotic SRP.
Mason
N
N
Wellcome Trust Centre for Cell Biology, Institute of Cell and Molecular Biology, University of Edinburgh, Swann Building, The King's Buildings, Mayfield Road, Edinburgh EH9 3JR, UK.
Ciufo
L F
LF
Brown
J D
JD
D001692:Biological Transport; D002451:Cell Compartmentation; D009154:Mutation; D010441:Peptide Chain Elongation, Translational; D016601:RNA-Binding Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D018271:Signal Recognition Particle / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
D016601:RNA-Binding Proteins; C089642:SRP14 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D018271:Signal Recognition Particle; C490325:Srp14 protein, mouse; C503637:Srp72 protein, mouse