Identification and characterization of a Drosophila nuclear proteasome activator: a homolog of human 11S REggamma (PA28gamma)
2001 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 276, no 2, 1383-1390 p.Article in journal (Refereed) Published
We report the cloning and characterization of aDrosophila proteasome 11 S REGγ (PA28) homolog. The 28-kDa protein shows 47% identity to the human REGγ and strongly enhances the trypsin-like activities of both Drosophila and mammalian 20 S proteasomes. Surprisingly, the DrosophilaREG was found to inhibit the proteasome's chymotrypsin-like activity against the fluorogenic peptide succinyl-LLVY-7-amino-4-methylcoumarin. Immunocytological analysis reveals that the Drosophila REG is localized to the nucleus but is distributed throughout the cell when nuclear envelope breakdown occurs during mitosis. Through site-directed mutagenesis studies, we have identified a functional nuclear localization signal present in the homolog-specific insert region. TheDrosophila PA28 NLS is similar to the oncogene c-Myc nuclear localization motif. Comparison between uninduced and innate immune induced Drosophila cells suggests that the REGγ proteasome activator has a role independent of the invertebrate immune system. Our results support the idea that γ class proteasome activators have an ancient conserved function within metazoans and were present prior to the emergence of the α and β REG classes.
Place, publisher, year, edition, pages
2001. Vol. 276, no 2, 1383-1390 p.
IdentifiersURN: urn:nbn:se:su:diva-22617DOI: 10.1074/jbc.M007379200OAI: oai:DiVA.org:su-22617DiVA: diva2:189171
Part of urn:nbn:se:su:diva-1012004-04-072004-04-072010-06-21Bibliographically approved