Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.25.1 (proteasome)
 28,817 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have identified two distinct subunits of 20 S proteasomes that are associated with RNase activity. Proteasome subunits zeta and iota, eluted from two-dimensional Western blots, hydrolysed tobacco mosaic virus RNA, whereas none of the other subunits degraded this substrate under the same conditions. Additionally, proteasomes were dissociated by 6 M urea, and subunit zeta, containing the highest RNase activity, was isolated by anion-exchange chromatography and gel filtration. Purified subunit zeta migrated as a single spot on two-dimensional PAGE with a molecular mass of approx. 28 kDa. Addition of anti-(subunit zeta) antibodies led to the co-precipitation of this proteasome subunit and nuclease activity. This is the first evidence that proteasomal alpha-type subunits are associated with an enzymic activity, and our results provide further evidence that proteasomes may be involved in cellular RNA metabolism.
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PMID:Involvement of proteasomal subunits zeta and iota in RNA degradation. 933 55

The ubiquitin-proteasome proteolytic pathway is involved in an important non-lysosomal proteolytic pathway that is responsible for the highly selective turnover of cellular proteins both under basal metabolic conditions as well as stress. Protein degradation by this pathway is attributed to the 20S proteasome that forms the catalytic core of the complex. Recently there has been increasing interest in the proteasome because of its possible role in neuron degeneration and death. Fetal Down syndrome (DS) neurons were demonstrated to degenerate and undergo apoptosis in vitro. We therefore investigated the expression of different proteins involved in this degradative pathway, including subunits of the 20S proteasome, ubiquitinating and deubiquitinating enzymes, and regulatory subunits of the 26S proteasome in control and DS fetal brains by two-dimensional electrophoresis (2-DE). After 2-DE, approximately 389 protein spots were successfully identified by matrix-associated laser desorption ionization mass spectroscopy (MALDI-MS) and this was followed by quantification of twenty three proteins of the pathway. The results indicate that all but two proteins exhibited no apparent alterations in their pattern of expression. Proteasome zeta chain, an alpha subunit of the 20S proteasome (P < 0.05) and ubiquitin carboxy-terminal hydrolase T (Isopeptidase T), a deubiquitinating enzyme (P < 0.001) were significantly increased in fetal DS compared to controls. Whilst the expression of proteasome iota (n = 9, r = -0.9489, P = 0.0004) and proteasome epsilon (n = 9, r = -0.7227, P = 0.0311) chains was decreased with age in fetal DS brain, no significant correlation was obtained in the other proteins with age. The data suggest that such selective upregulation may have relevance to the developmental abnormalities that characterize this disorder.
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PMID:Selective upregulation of the ubiquitin-proteasome proteolytic pathway proteins, proteasome zeta chain and isopeptidase T in fetal Down syndrome. 1177 38