We have shown that covalent conjugation of ubiquitin to proteins is temperature-sensitive in the mouse cell cycle mutant ts85 due to a specifically thermolabile ubiquitin-activating enzyme (accompanying paper). We show here that degradation of short-lived proteins is also temperature sensitive in ts85, in contrast to wild-type and revertant cells. While more than 70% of the prelabeled abnormal proteins (containing amino acid analogs) or puromycyl peptides are degraded within 4 hr at the permissive temperature in both ts85 and wild-type cells, less than 15% are degraded in ts85 cells at the nonpermissive temperature. Degradation of abnormal proteins and puromycyl peptides in both ts85 cells and wild-type cells is nonlysosomal and ATP-dependent. Immunochemical analysis shows a strong and specific reduction in the levels of in vivo labeled ubiquitin-protein conjugates at the nonpermissive temperature in ts85 cells. Degradation of normal, shortlived proteins is also specifically temperature sensitive in ts85. We suggest that the contribution of ubiquitin-independent pathways to the degradation of short-lived proteins in this higher eucaryotic cell is no more than 10%, and possibly less. © 1984.
CITATION STYLE
Ciechanover, A., Finley, D., & Varshavsky, A. (1984). Ubiquitin dependence of selective protein degradation demonstrated in the mammalian cell cycle mutant ts85. Cell, 37(1), 57–66. https://doi.org/10.1016/0092-8674(84)90300-3
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