Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.5.1.18 (glutathione S-transferase)
 22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cysteine proteases are involved in many diverse cellular processes ranging from processing of precursor proteins to intracellular degradation. In an effort to identify novel cysteine proteases, we used the polymerase chain reaction and primers directed against the catalytic sites of previously cloned cysteine proteases. From rat brain mRNA, a 600-base pair band was amplified; cloning and partial sequence analysis of this band resulted in the identification of cathepsins B and L and five novel sequences. The novel cDNAs contained a number of residues conserved in lysosomal cysteine proteases, including the active site residue His159 (papain numbering). In addition, the amino acid homology between the novel sequences and either cathepsins B, L, or H, ranged from 63 to 32%. The insert with highest homology was used to screen a rat brain cDNA library; a 1334-base pair cDNA was isolated and the nucleotide sequence determined. This sequence encodes an open reading frame of 330 amino acids which is 82% homologous to human cathepsin S, suggesting that this sequence represents rat cathepsin S. Northern blot analysis for rat cathepsin S revealed tissue-specific expression distinct from the distribution of cathepsin B and L. The regulation of expression of rat cathepsin S mRNA in response to thyroid-stimulating hormone was studied in a rat thyroid cell line FRTL-5. The level of cathepsin S mRNA was substantially increased in response to thyroid-stimulating hormone, whereas cathepsin B and cathepsin L mRNA levels were not altered by this treatment. A portion of cDNA encoding the predicted mature protein of rat cathepsin S was expressed as a glutathione S-transferase-fusion protein. The affinity-purified protein exhibited proteolytic activity with properties similar to bovine cathepsin S. Taken together, these results imply highly specific functions for cathepsin S.
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PMID:Sequence analysis, tissue distribution, and expression of rat cathepsin S. 128 81

The prodomains of several cysteine proteases of the papain family have been shown to be potent inhibitors of their parent enzymes. An increased interest in cysteine proteases inhibitors has been generated with potential therapeutic targets such as cathepsin K for osteoporosis and cathepsin S for immune modulation. The propeptides of cathepsin S, L and K were expressed as glutathione S-transferase-fusion proteins in Escherichia coli. The proteins were purified on glutathione affinity columns and the glutathione S-transferase was removed by thrombin cleavage. All three propeptides were tested for inhibitor potency and found to be selective within the cathepsin L subfamily (cathepsins K, L and S) compared with cathepsin B or papain. Inhibition of cathepsin K by either procathepsin K, L or S was time-dependent and occurred by an apparent one-step mechanism. The cathepsin K propeptide had a Ki of 3.6-6.3 nM for each of the three cathepsins K, L and S. The cathepsin L propeptide was at least a 240-fold selective inhibitor of cathepsin K (Ki = 0.27 nM) and cathepsin L (Ki = 0.12 nM) compared with cathepsin S (Ki = 65 nM). Interestingly, the cathepsin S propeptide was more selective for inhibition of cathepsin L (Ki = 0.46 nM) than cathepsin S (Ki = 7.6 nM) itself or cathepsin K (Ki = 7.0 nM). This is in sharp contrast to previously published data demonstrating that the cathepsin S propeptide is equipotent for inhibition of human cathepsin S and rat and paramecium cathepsin L [Maubach, G., Schilling, K., Rommerskirch, W., Wenz, I., Schultz, J. E., Weber, E. & Wiederanders, B. (1997), Eur J. Biochem. 250, 745-750]. These results demonstrate that limited selectivity of inhibition can be measured for the procathepsins K, L and S vs. the parent enzymes, but selective inhibition vs. cathepsin B and papain was obtained.
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PMID:Potency and selectivity of inhibition of cathepsin K, L and S by their respective propeptides. 1101 86

Cathepsin S is a critical protease for the regulation of MHC class II immune responses, and thus is a potential target for developing immunosuppressive drugs in the pathogenesis of degenerative and autoimmune diseases. In this study, we cloned a cDNA encoding for cathepsin S (PoCtS) from the olive flounder, Paralichthys olivaceus. The 1170 bp PoCtS cDNA contained an open reading frame of 1014 bp, which consisted of a 25-residue putative signal peptide, a 96-residue propeptide and the 216-residue mature enzyme. The tissue-specific expression pattern of PoCtS, determined via RT-PCR and real-time PCR analysis, revealed ubiquitous expression throughout the entirety of healthy flounder tissues; however IL-1beta, IL-6, IL-8 and PoCtS expression increased significantly in muscle 6h post-injection of bacterial lipopolysaccharide (LPS). The cDNA encoding proenzyme of PoCtS was expressed in Escherichia coli as a fusion protein with glutathione S-transferase in a pGEX-4T-1 vector. Also, the recombinant proPoCtS protein was overexpressed in E. coli BL21(DE3) as a 60 kDa fusion protein. Cathepsin S activity was detected through the cleavage of synthetic fluorogenic peptide substrates, such as Z-Val-Val-Arg-AMC and Z-Phe-Arg-AMC. The optimum pH for the protease activity was determined to be 8. This is the first report that characterized the enzymatic properties and analyzed the expression of piscine cathepsin S.
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PMID:Cloning, expression analysis and enzymatic characterization of cathepsin S from olive flounder (Paralichthys olivaceus). 2060 Oct 61