Thermolability of ubiquitin-activating enzyme from the mammalian cell cycle mutant ts85

Cell. 1984 May;37(1):43-55. doi: 10.1016/0092-8674(84)90299-x.


Ubiquitin, a 76 residue protein, occurs in eucaryotic cells either free or covalently joined to a variety of protein species. Previous work suggested that ubiquitin may function as a signal for attack by proteinases specific for ubiquitin-protein conjugates. We show that the mouse cell line ts85 , a previously isolated cell cycle mutant, is temperature-sensitive in ubiquitin-protein conjugation, and that this effect is due to the specific thermolability of the ts85 ubiquitin-activating enzyme (E1). From E1 thermoinactivation kinetics in mixed (wild-type plus ts85 ) extracts, and from copurification of the determinant of E1 thermolability with E1 in ubiquitin-affinity chromatography, we conclude that the determinant of E1 thermolability is contained within the E1 polypeptide. ts85 cells fail to degrade otherwise short-lived intracellular proteins at the nonpermissive temperature (accompanying paper), demonstrating that degradation of the bulk of short-lived proteins in this higher eucaryotic cell proceeds through a ubiquitin-dependent pathway. We discuss possible roles of ubiquitin-dependent pathways in DNA transactions, the cell cycle, and the heat shock response.

Publication types

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

MeSH terms

  • Animals
  • Cell Cycle*
  • Cell Line
  • Chromatography, Affinity
  • Chromosomal Proteins, Non-Histone / isolation & purification
  • Chromosomal Proteins, Non-Histone / metabolism
  • Female
  • Histones / metabolism
  • Hot Temperature
  • Ligases / metabolism*
  • Mammary Neoplasms, Experimental / physiopathology
  • Mice
  • Molecular Weight
  • Mutation*
  • Nucleoproteins / metabolism
  • Ubiquitin-Activating Enzymes
  • Ubiquitin-Protein Ligases
  • Ubiquitins


  • Chromosomal Proteins, Non-Histone
  • Histones
  • Nucleoproteins
  • Ubiquitins
  • Ubiquitin-Protein Ligases
  • Ligases
  • Ubiquitin-Activating Enzymes