期刊
ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS
卷 380, 期 2, 页码 360-366出版社
ACADEMIC PRESS INC
DOI: 10.1006/abbi.2000.1940
关键词
3-nitrotyrosine; proteasome; chymotrypsin; superoxide dismutase; tyrosine hydroxylase
资金
- NEI NIH HHS [EY11735] Funding Source: Medline
- NHLBI NIH HHS [HL54926] Funding Source: Medline
- NIA NIH HHS [AG13966] Funding Source: Medline
Tyrosine nitration is a covalent posttranslational protein modification that has been detected under several pathological conditions. This study reports that nitrated proteins are degraded by chymotrypsin and that protein nitration enhances susceptibility to degradation by the proteasome. Chymotrypsin cleaved the peptide bond between nitrated-tyrosine 108 and serine 109 in bovine Cu,Zn superoxide dismutase. However, the rate of chymotryptic cleavage of nitrated peptides was considerably slower than control. In contrast, nitrated bovine Cu,Zn superoxide dismutase was degraded at a rate 1.8-fold faster than that of control by a gradient-purified 20S/26S proteasome fraction from bovine retina. Exposure of PC12 cells to a nitrating agent resulted in the nitration of tyrosine hydroxylase and a 58 +/- 12.5% decline in the steady-state levels of the protein 4 h after nitration. The steady-state levels of tyrosine hydroxylase were restored by selective inhibition of the proteasome activity with lactacystin. These data indicate that nitration of tyrosine residue(s) in proteins is sufficient to induce an accelerated degradation of the modified proteins by the proteasome and that the proteasome may be critical for the removal of nitrated proteins in vivo. (C) 2000 Academic Press.
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