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

Cell. 2000 Jul 7;102(1):67-76. doi: 10.1016/s0092-8674(00)00011-8.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Arginine / genetics
  • Arginine / metabolism
  • Biopolymers / genetics
  • Biopolymers / metabolism*
  • Cell Cycle*
  • Cell Line, Transformed
  • Humans
  • Lysine / genetics
  • Lysine / metabolism
  • Magnesium Chloride / pharmacology
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Polyribosomes / metabolism
  • Polyubiquitin
  • Protein Biosynthesis
  • Ribosomal Proteins / metabolism*
  • Ribosomes / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins*
  • Ubiquitins / genetics
  • Ubiquitins / metabolism*


  • Biopolymers
  • RPL28 protein, S cerevisiae
  • RPL28 protein, human
  • Ribosomal Proteins
  • Saccharomyces cerevisiae Proteins
  • Ubiquitins
  • ribosomal protein S80
  • Magnesium Chloride
  • Polyubiquitin
  • Arginine
  • Lysine