Mitosis and protein synthesis 4 turnover of short- and long-lived proteins during the cell cycle of synchronized L-132 and HeLa S-3 cells.
Turnover rates of short- and long-lived proteins throughout the cell cycle were measured in two established mammalian cell lines, L-132 and HeLa S-3, using both selection and induction synchronization. Short-lived, newly synthesized proteins turned over at the same rate during all stages of the cell cycle when this rate was expressed as a percentage of total labelling of proteins present at the start of the chase. Since fewer proteins were made in M-phase, the absolute turnover rate was probably reduced to a small degree during division itself, indicating a close co-ordination between synthesis and degradation. In contrast, long-lived proteins showed a considerable reduction in their rate of turnover specifically during M-phase. One possible explanation for the reduced degradation of long-lived protein is the suppression of lysosomal activity during division, with no apparent effect on the turnover of short-lived proteins which is due to a non-lysosomal system.
Department of Pathology, University of Aberdeen, Foresterhill, Scotland, Great Britain.
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Wheatley
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Knecht
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Cervera
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Smith
D002453:Cell Cycle; D002461:Cell Line, Transformed; D004247:DNA / Q000096:biosynthesis; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D006367:HeLa Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008168:Lung; D008938:Mitosis; D011506:Proteins / Q000378:metabolism*
D011506:Proteins; D004247:DNA