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Gene Review

CTSK  -  cathepsin K

Homo sapiens

Synonyms: CTS02, CTSO, CTSO1, CTSO2, Cathepsin K, ...
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Disease relevance of CTSK


High impact information on CTSK

  • Primary lung fibroblasts derived from CTSK(-/-) mice showed a decreased collagenolytic activity indicating the role of catK in collagen degradation [6].
  • The population frequencies of haplotypes defined by these five polymorphisms were estimated, and a cladogram was derived showing proximity of relationship and likely descent of the 30 most common CTSK haplotypes [1].
  • Adjusted BMD values were not associated with simple tandem repeat (STR) markers or single nucleotide polymorphisms (SNPs) at the Cathepsin K (CTSK) locus [1].
  • However, there have been no studies of common genetic variants in CTSK and their possible association with bone density in the general population [1].
  • We performed linear regression analysis to identify and adjust for nongenetic predictors of BMD, and adjusted BMD values (regression residuals) were tested for association with individual CTSK markers and haplotypes by ANOVA and the composite haplotype method of Zaykin et al [1].

Biological context of CTSK

  • Genomic organization and chromosome localization of the human cathepsin K gene (CTSK) [7].
  • RESULTS AND CONCLUSIONS: We discovered two intronic SNPs (8% and 9% frequency), but no common exonic SNPs (> 1% frequency), and found that three STRs at the immediate 5' end of the CTSK locus are highly polymorphic [1].
  • The coding exons of the cathepsin K gene (CTSK) were amplified and sequenced [8].
  • From a model of the protease complexed with Cbz-FRF, the bound carboxypeptidase substrate is predicted to establish a number of favorable contacts within the cathepsin X binding site, in particular with residues His23 and Tyr27 from the mini-loop [9].
  • Cathepsin X is a novel cysteine protease which was identified recently from the EST (expressed sequence tags) database [9].

Anatomical context of CTSK


Associations of CTSK with chemical compounds


Enzymatic interactions of CTSK

  • Cathepsin L hydrolyzed the majority of them with similar or higher catalytic efficiency than cathepsin X, acting as an endopeptidase mimicking a carboxymonopeptidase (pseudo-carboxymonopeptidase) [14].

Other interactions of CTSK

  • To verify this hypothesis, human procathepsin X was expressed in Pichia pastoris and converted to mature cathepsin X using small amounts of human cathepsin L. Cathepsin X was found to display excellent carboxypeptidase activity against the substrate Abz-FRF(4NO(2)), with a k(cat)/K(M) value of 1.23 x 10(5) M(-)(1) s(-)(1) at the optimal pH of 5 [9].
  • Therefore, cathepsin X displays a stricter exopeptidase activity than cathepsin B. No inhibition of cathepsin X by cystatin C could be detected up to a concentration of 4 microM of inhibitor [9].

Analytical, diagnostic and therapeutic context of CTSK


  1. Characterization of common genetic variants in cathepsin K and testing for association with bone mineral density in a large cohort of perimenopausal women from Scotland. Giraudeau, F.S., McGinnis, R.E., Gray, I.C., O'Brien, E.J., Doncaster, K.E., Spurr, N.K., Ralston, S.H., Reid, D.M., Wood, J. J. Bone Miner. Res. (2004) [Pubmed]
  2. Human cathepsin O2, a matrix protein-degrading cysteine protease expressed in osteoclasts. Functional expression of human cathepsin O2 in Spodoptera frugiperda and characterization of the enzyme. Brömme, D., Okamoto, K., Wang, B.B., Biroc, S. J. Biol. Chem. (1996) [Pubmed]
  3. Carboxypeptidases cathepsins X and B display distinct protein profile in human cells and tissues. Kos, J., Sekirnik, A., Premzl, A., Zavasnik Bergant, V., Langerholc, T., Turk, B., Werle, B., Golouh, R., Repnik, U., Jeras, M., Turk, V. Exp. Cell Res. (2005) [Pubmed]
  4. Cathepsin K in adipocyte differentiation and its potential role in the pathogenesis of obesity. Xiao, Y., Junfeng, H., Tianhong, L., Lu, W., Shulin, C., Yu, Z., Xiaohua, L., Weixia, J., Sheng, Z., Yanyun, G., Guo, L., Min, L. J. Clin. Endocrinol. Metab. (2006) [Pubmed]
  5. Epithelial and stromal cathepsin K and CXCL14 expression in breast tumor progression. Kleer, C.G., Bloushtain-Qimron, N., Chen, Y.H., Carrasco, D., Hu, M., Yao, J., Kraeft, S.K., Collins, L.C., Sabel, M.S., Argani, P., Gelman, R., Schnitt, S.J., Krop, I.E., Polyak, K. Clin. Cancer Res. (2008) [Pubmed]
  6. Pivotal role of cathepsin K in lung fibrosis. Bühling, F., Röcken, C., Brasch, F., Hartig, R., Yasuda, Y., Saftig, P., Brömme, D., Welte, T. Am. J. Pathol. (2004) [Pubmed]
  7. Genomic organization and chromosome localization of the human cathepsin K gene (CTSK). Rood, J.A., Van Horn, S., Drake, F.H., Gowen, M., Debouck, C. Genomics (1997) [Pubmed]
  8. High bone mineral density in pycnodysostotic patients with a novel mutation in the propeptide of cathepsin K. Schilling, A.F., Mülhausen, C., Lehmann, W., Santer, R., Schinke, T., Rueger, J.M., Amling, M. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA (2007) [Pubmed]
  9. Human cathepsin X: A cysteine protease with unique carboxypeptidase activity. Nägler, D.K., Zhang, R., Tam, W., Sulea, T., Purisima, E.O., Ménard, R. Biochemistry (1999) [Pubmed]
  10. Cloning and complete coding sequence of a novel human cathepsin expressed in giant cells of osteoclastomas. Li, Y.P., Alexander, M., Wucherpfennig, A.L., Yelick, P., Chen, W., Stashenko, P. J. Bone Miner. Res. (1995) [Pubmed]
  11. Gene array identification of osteoclast genes: differential inhibition of osteoclastogenesis by cyclosporin A and granulocyte macrophage colony stimulating factor. Day, C.J., Kim, M.S., Stephens, S.R., Simcock, W.E., Aitken, C.J., Nicholson, G.C., Morrison, N.A. J. Cell. Biochem. (2004) [Pubmed]
  12. Peptidyl vinyl sulphones: a new class of potent and selective cysteine protease inhibitors: S2P2 specificity of human cathepsin O2 in comparison with cathepsins S and L. Brömme, D., Klaus, J.L., Okamoto, K., Rasnick, D., Palmer, J.T. Biochem. J. (1996) [Pubmed]
  13. Cathepsin X binds to cell surface heparan sulfate proteoglycans. Nascimento, F.D., Rizzi, C.C., Nantes, I.L., Stefe, I., Turk, B., Carmona, A.K., Nader, H.B., Juliano, L., Tersariol, I.L. Arch. Biochem. Biophys. (2005) [Pubmed]
  14. Recombinant human cathepsin X is a carboxymonopeptidase only: a comparison with cathepsins B and L. Puzer, L., Cotrin, S.S., Cezari, M.H., Hirata, I.Y., Juliano, M.A., Stefe, I., Turk, D., Turk, B., Juliano, L., Carmona, A.K. Biol. Chem. (2005) [Pubmed]
  15. Human cathepsin O2, a novel cysteine protease highly expressed in osteoclastomas and ovary molecular cloning, sequencing and tissue distribution. Brömme, D., Okamoto, K. Biol. Chem. Hoppe-Seyler (1995) [Pubmed]
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