Cell cycle-regulated modification of the ribosome by a variant multiubiquitin chain

Jean Spence, Rayappa Reddy Gali, Gunnar Dittmar, Fred Sherman, Michael Karin, Daniel Finley*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

322 Citations (Scopus)


Ubiquitin is ligated to L28, a component of the large ribosomal subunit, to form the most abundant ubiquitin-protein conjugate in S. cerevisiae. The human ortholog of L28 is also ubiquitinated, indicating that this modification is highly conserved in evolution. During S phase of the yeast cell cycle, L28 is strongly ubiquitinated, while reduced levels of L28 ubiquitination are observed in G1 cells. L28 ubiquitination is inhibited by a Lys63 to Arg substitution in ubiquitin, indicating that L28 is modified by a variant, Lys63-linked multiubiquitin chain. The K63R mutant of ubiquitin displays defects in ribosomal function in vivo and in vitro, including a dramatic sensitivity to translational inhibitors. L28, like other ribosomal proteins, is metabolically stable. Therefore, these data suggest a regulatory role for multiubiquitin chains that is reversible and does not function to target the acceptor protein for degradation.

Original languageEnglish
Pages (from-to)67-76
Number of pages10
Issue number1
Publication statusPublished - 7 Jul 2000
Externally publishedYes


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