Signal recognition particle components in the nucleolus

• DOI: 10.1073/pnas.97.1.55
• Publication Date: 2002-07-26T14:38:21Z
• Authors: Joan C. Politz; Serge Yarovoi; Susan M. Kilroy; Krishne Gowda; Christian Zwieb; Thoru Pederson
• Keywords: Signal recognition particle; Ribonucleoprotein particle

The signal recognition particle (SRP) is a ribonucleoprotein composed of an Alu domain and S domain. contains unique sequence SRP RNA four proteins: SRP19, SRP54, SRP68, SRP72. interacts with ribosomes to bring translating membrane secreted proteins the endoplasmic reticulum (ER) for proper processing. Additionally, member family small nonribosomal RNAs found recently in nucleolus, suggesting that nucleolus more plurifunctional than previously realized. It was therefore interest determine whether other components localize this intranuclear site. In transfected rat fibroblasts, green fluorescent protein fusions SRP72 localized as well cytoplasm, expected. SRP68 also accumulated ER, consistent its affinity ER-bound receptor. SRP54 detected cytoplasm fusion immunofluorescence studies, but not nucleolus. situ hybridization experiments revealed endogenous These results demonstrate three visit partial assembly, or another unidentified activity components, occurs at apparently nascent beyond vitro reconstitution showing SRP19 must bind before binds. Our findings support notion site assembly and/or interaction between ribonucleoproteins involved synthesis, addition themselves.