Access to ribosomal protein Rpl25p by the signal recognition particle is required for efficient cotranslational translocation.
Targeting of proteins to the endoplasmic reticulum (ER) occurs cotranslationally necessitating the interaction of the signal recognition particle (SRP) and the translocon with the ribosome. Biochemical and structural studies implicate ribosomal protein Rpl25p as a major ribosome interaction site for both these factors. Here we characterize an RPL25GFP fusion, which behaves as a dominant mutant leading to defects in co- but not posttranslational translocation in vivo. In these cells, ribosomes still interact with ER membrane and the translocon, but are defective in binding SRP. Overexpression of SRP can restore ribosome binding of SRP, but only partially rescues growth and translocation defects. Our results indicate that Rpl25p plays a critical role in the recruitment of SRP to the ribosome.
Dalley
Jane A
JA
Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT, United Kingdom.
Selkirk
Alexander
A
Pool
Martin R
MR
D004721:Endoplasmic Reticulum / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008954:Models, Biological; D018832:Molecular Chaperones / Q000737:chemistry; D009154:Mutation; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D021381:Protein Transport; D012269:Ribosomal Proteins / Q000378:metabolism / Q000502:physiology*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000502:physiology; D018271:Signal Recognition Particle / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism
D018832:Molecular Chaperones; D012269:Ribosomal Proteins; D018271:Signal Recognition Particle; C031127:ribosomal protein L25; D049452:Green Fluorescent Proteins