Human Cathepsin K,cath-K ELISA Kit

Code CSB-E09438h
Size 96T,5×96T,10×96T
Trial Size 24T ELISA kits trial application
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Product Details


This human CTSK ELISA kit employs the quantitative sandwich enzyme immunoassay technique to measure the levels of human CTSK in multiple samples, including serum, plasma, or tissue homogenates. The enzyme-substrate chromogenic reaction is also used to amplify the signal and quantify the levels of the analyte through the intensity of the colored product. The color intensity positively correlates with the amount of CTSK bound in the initial step.

CTSK is a cysteine proteinase that is primarily expressed in osteoclasts and mainly functions to mediate bone resorption. CTSK cleaves key bone matrix proteins like type I collagen and plays an important role in degrading the organic phase of bone during bone resorption. Mutations in the CTSK gene lead to an autosomal recessive osteosclerotic skeletal disorder-pycnodysostosis. CTSK is involved in cartilage matrix degradation and osteoarthritis (OA) because it also degrades type II collagen, the predominant matrix protein of cartilage.

Target Name cathepsin K
Alternative Names Cathepsin K ELISA Kit; Cathepsin O ELISA Kit; Cathepsin O1 ELISA Kit; Cathepsin O2 ELISA Kit; Cathepsin X ELISA Kit; CATK_HUMAN ELISA Kit; CTS02 ELISA Kit; Ctsk ELISA Kit; CTSO ELISA Kit; CTSO1 ELISA Kit; CTSO2 ELISA Kit; MGC23107 ELISA Kit; PKND ELISA Kit; PYCD ELISA Kit
Abbreviation CTSK
Uniprot No. P43235
Species Homo sapiens (Human)
Sample Types serum, plasma, tissue homogenates
Detection Range 7.8 pg/mL-500 pg/mL
Sensitivity 1.95 pg/mL
Assay Time 1-5h
Sample Volume 50-100ul
Detection Wavelength 450 nm
Research Area Signal Transduction
Assay Principle quantitative
Measurement Sandwich
Intra-assay Precision (Precision within an assay): CV%<8%
Three samples of known concentration were tested twenty times on one plate to assess.
Inter-assay Precision (Precision between assays): CV%<10%
Three samples of known concentration were tested in twenty assays to assess.
To assess the linearity of the assay, samples were spiked with high concentrations of human cath-K in various matrices and diluted with the Sample Diluent to produce samples with values within the dynamic range of the assay.
1:1Average %97
Range %92-105
1:2Average %92
Range %88-98
1:4Average %85
Range %80-90
1:8Average %95
Range %91-100
The recovery of human cath-K spiked to levels throughout the range of the assay in various matrices was evaluated. Samples were diluted prior to assay as directed in the Sample Preparation section.
Sample TypeAverage % RecoveryRange
Serum (n=5) 9690-102
EDTA plasma (n=4)9588-99
Typical Data
These standard curves are provided for demonstration only. A standard curve should be generated for each set of samples assayed.
5001.886 1.822 1.854 1.735
2501.568 1.489 1.529 1.410
1251.213 1.201 1.207 1.088
62.50.976 0.939 0.958 0.839
31.20.652 0.624 0.638 0.519
15.60.348 0.325 0.337 0.218
7.80.206 0.199 0.203 0.084
00.121 0.117 0.119  
ELISA Data Analysis Watch ELISA data processing video & download Curve Expert if needed
and FAQs
Storage Store at 2-8°C. Please refer to protocol.
Lead Time 3-5 working days

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Target Background

(From Uniprot)
Thiol protease involved in osteoclastic bone resorption and may participate partially in the disorder of bone remodeling. Displays potent endoprotease activity against fibrinogen at acid pH. May play an important role in extracellular matrix degradation. Involved in the release of thyroid hormone thyroxine (T4) by limited proteolysis of TG/thyroglobulin in the thyroid follicle lumen.
Gene References into Functions
  1. Sclerostin is degraded by cathepsin K in vitro. Cathepsin K degradation of sclerostin is affected by hypoxia. PMID: 29859187
  2. Upregulation of CTSK seems to be associated with high incidence of lymphatic spread and poor survival in OSCC. CTSK could therefore serve as a predictive biomarker for OSCC. PMID: 29618339
  3. our data showed that elevated Cathepsin K in epithelial ovarian cancer can potentiate the metastasis of epithelial ovarian cancer cells PMID: 29303207
  4. results highlight the possibility that the interaction between GAGs and collagen under acidic conditions has a regulatory impact on cathepsin K-mediated bone degradation. PMID: 29029096
  5. measurement of a periostin fragment resulting from in vivo cathepsin K digestion may help to identify subjects at high risk of fracture. PMID: 28766739
  6. cathepsin K in the development of chronic subdural hematoma PMID: 28887075
  7. Cathepsin K expression within the subchondral bone of the medial tibia plateau was not associated with osteoclast density or symptomatic knee osteoarthritis. PMID: 28087412
  8. The enhanced invasion of carcinomas resulting from cathepsin K overexpression is probably due to the increased cell migration and adhesion. Thus, cathepsin K is implicated not only in protein degradation but also in invasion, migration and adhesion of oral squamous cell carcinomas. PMID: 28117540
  9. positive expression of cathepsin K in melanoma of the skin is associated with other unfavorable prognostic factors PMID: 27709599
  10. Patients affected by castration-resistant prostate carcinoma may be tested for cathepsin K, and a positive strong expression (2+) could be a useful predictive biomarker of response to targeted agents, aiding in the selection of patients eligible for these treatments. PMID: 28085175
  11. Of 160 top compounds tested in enzymatic assays, 28 compounds showed blocking of the collagenase activity of Cathepsin K (CatK) at 100 muM. PMID: 29088253
  12. Cathepsin K cleavage of SDF-1alpha inhibits its chemotactic activity towards glioblastoma stem-like cells. PMID: 28040478
  13. Increased cathepsin K expression in skull base chordoma was associated with tumor invasion and reduced progression free survival. PMID: 28216213
  14. Immunohistochemistry confirmed cathepsin K protein was expressed in lymphangioleiomyomatosis but not control lungs. Cathepsin K gene expression and protein and protease activity were detected in lymphangioleiomyomatosis -associated fibroblasts but not the LAM cell line 621-101. PMID: 28623674
  15. The allosteric site of cathepsin K has been modified by site-directed mutagenesis, and it was shown that it is involved in specific regulation of the collagenolytic activity of cathepsin K. PMID: 27859061
  16. Cathepsin K and osteocalcin plasma levels may be suggested as the significant markers of osteopoenia/osteoporosis. In addition, cathepsin K plasma level can be also a valuable marker of severe Coronary Atherosclerosis and Coronary Artery Calcification . PMID: 26988144
  17. Six mutations in CTSK were identified in 33 families with pycnodysostosis. The high frequency of pycnodysostosis in Ceara State is the consequence of the high inbreeding in that region. PMID: 27558267
  18. The above studies not only demonstrated that CTSK was widely expressed in tooth-related cells (including odonto- clasts, periodontal ligament cells, pulp cells and odonto- blasts), but also indicated that CTSK was closely related to the development of tissues in oral and maxillofacial region as well as occurrence and development of many oral diseases. PMID: 26458004
  19. This mutation (c.480_481insT), (p.L160fsX173) is a novel frameshift mutation. The index case extends the phenotypic spectrum and the list of previously reported mutations in the CTSK gene. PMID: 25304337
  20. There is an increase in levels of CATK in type 1 Gaucher patients compared to the control group. In the patient group, CATK showed higher levels in patients with bone damage compared to those without it. PMID: 25662720
  21. increased expression and activation in osteoarthritis cartilage PMID: 26241216
  22. elevated levels of CatK are closely associated with the presence of chronic heart failure and that the measurement of circulating CatK provides a noninvasive method of documenting and monitoring the extent of chronic heart failure PMID: 26302400
  23. Cathepsins in Rotator Cuff Tendinopathy: Identification in Human Chronic Tears and Temporal Induction in a Rat Model. PMID: 25558848
  24. The study determined almost identical substrate specificities for cysteine cathepsins K, L and S. PMID: 25626674
  25. Matrix-metalloproteinase-9 is cleaved and activated by cathepsin K. PMID: 26219353
  26. Sequence analysis of the patient's CTSK gene revealed homozygosity for a missense mutation (c.746T>C) in exon 6, which leads to amino change (p.Ile249Thr) in the mature CTSK protein PMID: 25725806
  27. The presence of high levels of inactive proforms of cathepsin K in GBM tissues and cells indicate that in GBM the proteolytic/collagenolytic role is not its primary function but it plays rather a different yet unknown role. PMID: 25356585
  28. Two compounds have sizable effects on enzyme activity using interstitial collagen as a natural substrate of cathepsin K and four compounds show a significantly stabilizing effect on cathepsin K. PMID: 25184245
  29. Studies indicate cathepsin X as a target for improving diagnosis and treating cancer patients. PMID: 24835450
  30. SDF-1alpha is involved in homing of CXCR4+ GSLCs and leukocytes and that cathepsin K and osteopontin are involved in the migration of GSLCs out of the niches PMID: 25809793
  31. one cathepsin K molecule binds to collagen-bound glycosaminoglycans at the gap region and recruits a second protease molecule that provides an unfolding and cleavage mechanism for triple helical collagen PMID: 25422423
  32. The identification of CatK exosites opens up the prospect of designing highly potent inhibitors that selectively inhibit the degradation of therapeutically relevant substrates by this multifunctional protease. PMID: 25279554
  33. The data indicated that elevated levels of cathepsin K are closely associated with the presence of CAD and that circulating cathepsin K serves a useful biomarker for CAD. PMID: 24954318
  34. synergism between HIV proteins and pro-atherogenic shear stress to increase endothelial cell expression of the powerful protease cathepsin K PMID: 24719048
  35. Cathepsin K appears to be consistently and strongly expressed in melanocytic lesions and valuable in distinguishing malignant melanomas from the majority of human cancers. PMID: 24696729
  36. results demonstrate that CS plays an important role in contributing to the enhanced efficiency of CatK collagenase activity in vivo PMID: 24958728
  37. identified five CTSK missense mutations (M1I, I249T, L7P, D80Y and D169N), one nonsense mutation (R312X) and one 301 bp insertion in intron 7, which is revealed as Alu sequence; among them, only L7P and I249 were described previously PMID: 24767306
  38. Expression of cathepsins K, S and V within keratinocytes is reduced in photoprotected skin of aged women. PMID: 23871919
  39. The use of exome sequencing in the molecular diagnosis of 2 siblings initially thought to be affected by "intermediate osteopetrosis", which identified a homozygous mutation in the CTSK gene, is described. PMID: 24269275
  40. Data indicate that cathepsin K is expressed in oral tongue squamous cell carcinoma (OTSCC) tissue in both carcinoma and tumor microenvironment (TME) cells. PMID: 23951042
  41. Increased plasma CatK levels are linked with the presence of atrial fibrillation. PMID: 24342995
  42. Skipping of the 121-bp exon 2 results in elimination of the normal start codon and an expected absence of the wild-type CTSK protein. PMID: 24134756
  43. catalase expression (or activity) was higher, while intracellular and extracellular Cat S, Cat L, and Cat K activities were lower in the non-invasive CL1-0 cells compared to the highly invasive CL1-5 cells. PMID: 24583396
  44. Identification of a novel insertional frameshift mutation in exon 4 of the CTSK gene in two families with pycnodysostosis. PMID: 23689398
  45. The basic amino acid clusters in cathepsin K play roles in the formation of collagenolytically active protease complexes. PMID: 24088021
  46. These data indicated that high levels of CatK are closely linked with the presence of coronary artery disease. PMID: 23369704
  47. Our results demonstrate that increased adhesion, migration and invasiveness of tumor cells depend on the inactivation of the tumor suppressive function of profilin 1 by cathepsin X. PMID: 23326535
  48. Cardiac mammalian target of rapamycin and extracellular signal-regulated kinases (ERK) signaling cascades were upregulated by pressure overload, the effects of which were attenuated by cathepsin K knockout. PMID: 23529168
  49. Cathepsin X deficiency leads to a reduced phosphorylation of the IGF-I receptor in response to IGF-I stimulation. PMID: 23152410
  50. show for the first time that bone marrow macrophage-supplied CTSK may be involved in CCL2- and COX-2-driven pathways that contribute to tumor progression in bone PMID: 22614014

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Involvement in disease Pycnodysostosis (PKND)
Subcellular Location Lysosome. Secreted. Apical cell membrane; Peripheral membrane protein; Extracellular side.
Protein Families Peptidase C1 family
Tissue Specificity Predominantly expressed in osteoclasts (bones). Expressed in thyroid epithelial cells.
Database Links

HGNC: 2536

OMIM: 265800

KEGG: hsa:1513

STRING: 9606.ENSP00000271651

UniGene: Hs.632466

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