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Ubiquitinated protein conjugates are specifically enriched in the lysosomal system of fibroblasts
Author(s) -
Laszlo Lajos,
Doherty Fergus J.,
Osborn Natasha U.,
John Mayer R.
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80593-8
Subject(s) - ubiquitin , compartment (ship) , microbiology and biotechnology , biochemistry , chemistry , lysosome , conjugate , ddb1 , protease , cysteine protease , biology , ubiquitin ligase , enzyme , gene , geology , mathematical analysis , oceanography , mathematics
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.