Ubiquitinated protein conjugates are specifically enriched in the lysosomal system of fibroblasts
- 26 February 1990
- journal article
- Published by Wiley in FEBS Letters
- Vol. 261 (2) , 365-368
- https://doi.org/10.1016/0014-5793(90)80593-8
Abstract
Ubiquitin-protein conjugates are found by imniunogold electron microscopy to be enriched (12-fold) in the lysosomal compartment of 3T3-L1 fibroblasts. Treatment of fibroblasts with the cysteine protease inhibitor E-64 leads to an expansion of the lysosomal compartment and as a result an increase in the cellular content of ubiquitin-protein conjugates. There is no change in the specific enrichment of ubiquitin-protein conjugates in the lysosomal compartment following E-64 treatment. The results suggest that some ubiquitin-protein conjugates may normally be degraded lysosomally following sequestration by microautophagy and imply that protein ubiquitination may be one of the signals for protein uptake into lysosomes.Keywords
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