Author:
Slot L A,Lauridsen A M B,Hendil K B
Abstract
IMR90 human fibroblasts were labelled by incubation of cells for 48 h in medium containing 10% serum and [3H]leucine. The labelled protein was degraded at a rate of 1%/h during a subsequent incubation in medium with 10% serum. Incubation in medium without serum caused a transient enhancement of the degradation of endogenous protein, which was also found in cells labelled in medium without serum. The degradation of micro-injected haemoglobin was enhanced by serum deprivation in a non-transient manner. These results suggest that enhanced degradation in serum-free medium occurs only for a subpopulation of cell proteins and that it appears transient because the major part of the pool of susceptible endogenous proteins is being degraded during the first 20-30 h in serum-free unlabelled medium. Protein turnover in various cell compartments was measured by a double-labelling technique. Most of the enhanced degradation in serum-deprived cultures (73-83%) was due to breakdown of cytosolic proteins. The enhanced degradation of cytosolic proteins seemed to affect several proteins irrespective of their molecular mass or metabolic stability.
Subject
Cell Biology,Molecular Biology,Biochemistry
Cited by
30 articles.
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