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Direct evidence for nuclear and cytoplasmic colocalization of proteasomes (Multiprotease complexes) in liver

Direct evidence for nuclear and cytoplasmic colocalization of proteasomes (Multiprotease... 10.1002/jcp.1041390107.abs Subcellular localization of the large multicatalytic protease complexes called proteasomes, which have been found in soluble fractions of various cells, was examined by biochemical, immunological, and immunohistological methods. Rat liver nuclei, purified by two different procedures, showed high activities for degrading (3H)methylcasein and various fluorogenic oligopeptides with neutral and weakly alkaline pH optima. On gel filtration, all of these peptidase activities were recovered in a single peak with the unusually large molecular weight of about 600,000. Properties of the proteolytic activity in crude extracts of the nucleus and the cytoplasm were very similar. Immunoelectrophoretic blot analysis showed the presence of appreciable concentrations of proteasomes with similar immunoreactivity in isolated nuclear and cytosolic fractions. Moreover, immunohistochemical staining of human liver showed that proteasomes were predominantly localized in the nuclear matrix but also were present diffusely in the cytoplasm of hepatocytes. These findings indicate the nuclear and cytoplasmic colocalization of proteasomes. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Cellular Physiology Wiley

Direct evidence for nuclear and cytoplasmic colocalization of proteasomes (Multiprotease complexes) in liver

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References (33)

Publisher
Wiley
Copyright
Copyright © 1989 Wiley‐Liss, Inc.
ISSN
0021-9541
eISSN
1097-4652
DOI
10.1002/jcp.1041390107
pmid
2651460
Publisher site
See Article on Publisher Site

Abstract

10.1002/jcp.1041390107.abs Subcellular localization of the large multicatalytic protease complexes called proteasomes, which have been found in soluble fractions of various cells, was examined by biochemical, immunological, and immunohistological methods. Rat liver nuclei, purified by two different procedures, showed high activities for degrading (3H)methylcasein and various fluorogenic oligopeptides with neutral and weakly alkaline pH optima. On gel filtration, all of these peptidase activities were recovered in a single peak with the unusually large molecular weight of about 600,000. Properties of the proteolytic activity in crude extracts of the nucleus and the cytoplasm were very similar. Immunoelectrophoretic blot analysis showed the presence of appreciable concentrations of proteasomes with similar immunoreactivity in isolated nuclear and cytosolic fractions. Moreover, immunohistochemical staining of human liver showed that proteasomes were predominantly localized in the nuclear matrix but also were present diffusely in the cytoplasm of hepatocytes. These findings indicate the nuclear and cytoplasmic colocalization of proteasomes.

Journal

Journal of Cellular PhysiologyWiley

Published: Apr 1, 1989

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