Three novel components of the human exosome

Rick Brouwer, Christine Allmang, Reinout Raijmakers, Yvonne Van Aarssen, Wilma Vree Egberts, Elisabeth Petfalski, Walther J. Van Venrooij, David Tollervey, Ger J.M. Pruijn

Research output: Contribution to journalArticlepeer-review

Abstract

The yeast exosome is a complex of 3′ → 5′ exoribonucleases. Sequence analysis identified putative human homologues for exosome components, although several were found only as expressed sequence tags. Here we report the cloning of full-length cDNAs, which encode putative human homologues of the Rrp40p, Rrp41p, and Rrp46p components of the exosome. Recombinant proteins were expressed and used to raise rabbit antisera. In Western blotting experiments, these decorated HeLa cell proteins of the predicted sizes. All three human proteins were enriched in the HeLa cells nucleus and nucleolus, but were also clearly detected in the cytoplasm. Size exclusion chromatography revealed that hRrp40p, hRrp41p, and hRrp46p were present in a large complex. This cofractionated with the human homologues of other exosome components, hRrp4p and PM/ Scl-100. Anti-PM/Scl-positive patient sera coimmunoprecipitated hRrp40p, hRrp41p, and hRrp46p demonstrating their physical association. The immunoprecipitated complex exhibited 3′ → 5′ exoribonuclease activity in vitro. hRrp41p was expressed in yeast and shown to suppress the lethality of genetic depletion of yeast Rrp41p. We conclude that hRrp40p, hRrp41p, and hRrp46p represent novel components of the human exosome complex.

Original languageEnglish
Pages (from-to)6177-6184
Number of pages8
JournalJournal of Biological Chemistry
Volume276
Issue number9
DOIs
Publication statusPublished - 10 Nov 2000

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