Recombinant Human Cystatin B Protein (His Tag)

Beta LifeScience SKU/CAT #: BLPSN-1528

Recombinant Human Cystatin B Protein (His Tag)

Beta LifeScience SKU/CAT #: BLPSN-1528
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Product Overview

Tag His
Host Species Human
Accession P04080
Background Cystatin-B, also known as CPI-B, Liver thiol proteinase inhibitor, Stefin-B, CSTB and CST6, is a cytoplasm and nucleus protein which belongs to thecystatin family. Cystatin-B / CSTB is an intracellular thiol proteinase inhibitor. Tightly binding reversible inhibitor of cathepsins L, H and B. Cystatin-B / CSTB is able to form a dimer stabilized by noncovalent forces, inhibiting papain and cathepsins l, h and b. Cystatin-B / CSTB is also thought to play a role in protecting against the proteases leaking from lysosomes. Defects in Cystatin-B / CSTB are the cause of progressive myoclonic epilepsy type 1 (EPM1) which is an autosomal recessive disorder characterized by severe, stimulus-sensitive myoclonus and tonic-clonic seizures. The cystatins are a family of cysteine protease inhibitors with homology to chicken cystatin. Cystatins are physiological inhibitors of cysteine proteinases which are widely distributed in human tissues and fluids. Cystatins typically comprise about 115 amino acids, are largely acidic, contain four conserved cysteine residues known to form two disulfide bonds. Cystatins may be glycosylated and / or phosphorylated, with similarity to fetuins, kininogens, stefins, histidine-rich glycoproteins and cystatin-related proteins. Some of the members are active cysteine protease inhibitors, while others have lost or perhaps never acquired inhibitory activity. Cystatins mainly inhibit peptidases belonging to peptidase families C1 (papain family) and C13 (legumain family).
Description A DNA sequence encoding the human CSTB (P04080) (Met 2-Phe 98) was expressed, with a His tag at the N-terminus.
Source E.coli
Predicted N Terminal Met
AA Sequence Met 2-Phe 98
Molecular Weight The recombinant human CSTB consisting of 108 a.a. and has a calculated molecular mass of 12.5 kDa. It migrates as an approximately 15 kDa band in SDS-PAGE under reducing conditions.
Purity >95% as determined by SDS-PAGE
Endotoxin Please contact us for more information.
Bioactivity Measured by its ability to inhibit papain cleavage of a fluorogenic peptide substrate Z-FR-AMC (R&D Systems, Catalog # ES009). The IC50 value is < 15 nM.
Formulation Lyophilized from sterile 50mM Tris, 50mM NaCl, pH 8.0.
Stability The recombinant proteins are stable for up to 1 year from date of receipt at -70°C.
Usage For Research Use Only
Storage Store the protein under sterile conditions at -20°C to -80°C. It is recommended that the protein be aliquoted for optimal storage. Avoid repeated freeze-thaw cycles.

Target Details

Target Function This is an intracellular thiol proteinase inhibitor. Tightly binding reversible inhibitor of cathepsins L, H and B.
Subcellular Location Cytoplasm. Nucleus.
Protein Families Cystatin family
Database References
Associated Diseases Epilepsy, progressive myoclonic 1 (EPM1)

Gene Functions References

  1. cystatin B expression was significantly and inversely correlated with lung tumor stage and tumor grade PMID: 29037838
  2. The results demonstrate that cystatin B interferes with the STAT-1 signaling and IFN-beta-antiviral responses perpetuating HIV in macrophage reservoirs. PMID: 27137788
  3. apoptosis is accompanied by degradation of the cysteine cathepsin inhibitor stefin B (StfB). CatD did not exhibit a crucial role in this step. However, this degradation was partially prevented through pre-incubation with the antioxidant N-acetyl cysteine PMID: 28543404
  4. Homozygous for a c.218dupT (p.His75Serfs*2) mutation in exon 3 of CSTB causes neurodegeneration, progressive cerebral volume loss and diffuse hypomyelination. PMID: 28378817
  5. CSTB downregulation may promote the development of gastric cancer. PMID: 28281969
  6. It was shown that decreased expression of cystatin B enhances cathepsin activity in Niemann-Pick C cerebellar degeneration patient fibroblasts. PMID: 26908626
  7. High expression of stefin B may be an important factor contributing to the development and metastasis of Hepatocellular Carcinoma. PMID: 26753874
  8. CSTB null mutation associated with microcephaly, early developmental delay, and severe dyskinesia. PMID: 26843564
  9. Data shows that CYTB and ANXA4 overexpression may be involved in carcinogenesis and histopathological differentiation of ovarian clear cell carcinoma and suggest they may serve as a potential diagnostic biomarkers. PMID: 25633807
  10. A role for disease-causing mutations in cystatin B gene in patients with juvenile myoclonic epilepsy was not supported. PMID: 25752200
  11. Even though the majority of EPM1 patients have a uniform genetic mutation, the actual size of the longer CSTB expansion mutation allele is likely to have a modulating effect on the age at disease onset, myoclonus severity, and cortical neurophysiology. PMID: 25770194
  12. The study shows detection of stefin B dimers in HEK293 cells and the importance of their residual activity. PMID: 25047918
  13. glutamate dehydrogenase is a euchromatin-associated enzyme, and its H3 clipping activity is regulated by chromatin structure, histone modifications and an in vivo inhibitor. PMID: 25263734
  14. detected a homozygous expansion of dodecamer repeats in the CSTB gene in four patients with clinical diagnosis of ULD. PMID: 23883076
  15. The increased CSTB expression in ovarian tissue represents tumor progression and is dysregulated by the TGF-beta signaling pathway. PMID: 24452274
  16. A reciprocal influence of CSTB and SOD1 at the gene expression level and for a direct interaction of the two proteins, is reported. PMID: 24234043
  17. The present study was performed on two more missense mutants of human stefin B, G50E and Q71P, and they similarly showed numerous aggregates upon overexpression. PMID: 24909779
  18. The co-localization of stefin B wild type and EPM1 mutants with cathepsins showed that cathepsins accumulate around the aggregates formed by the EPM1 mutants. PMID: 23362198
  19. Skull thickening and an increased prevalence of abnormal findings in skeletal radiographs of patients with EPM1 suggest that this condition is connected to defective cystatin B function. PMID: 23010349
  20. This study suggested that CSTB mutations other than the common dodecamer expansion predict particular phenotypes, including marked seizure severity and polymorphous seizure types. PMID: 23205931
  21. Elevated StefA mRNA level is associated with invasive glioblastoma. PMID: 22287159
  22. S-glutathionylation and S-cysteinylation were described as extensive PTM of a salivary protein and the first time that these PTMs were detected in naturally occurring cystatin B. PMID: 22057043
  23. patients compound heterozygous for the dodecamer repeat expansion and the c.202C>T mutations seem to have a severer form of Unverricht-Lundborg disease (EPM1) than patients homozygous for the expansion mutation PMID: 21757863
  24. At pH 7.0 the mutant H75W folded in three kinetic phases to a native-like intermediate, analogous to folding of stefin B at pH 4.8. PMID: 22033403
  25. Intracellular stefin b aggregation shows a negative correlation with cell survival PMID: 20078424
  26. Stefin B interacts with histones and cathepsin L in the nucleus PMID: 20075068
  27. oligomers of stefin B and amyloid-beta interact in vitro and in cells PMID: 19955183
  28. Oligonucleotides containing EPM1 repeat adopt secondary structures that may facilitate strand slippage thereby causing the expansion. PMID: 11697734
  29. Intramolecular i-motif structure at acidic pH for progressive myoclonus epilepsy (EPM1) repeat d(CCCCGCCCCGCG)n. PMID: 11697735
  30. analysed eight markers flanking CSTB(GT10-D21S1890-D21S1885-D21S2040-D21S1259- CSTB-D21S1912-PFKL-D21S171) and one intragenic variant in the CSTB 3' UTR (A2575G) PMID: 12215838
  31. first demonstration of cysteine protease activity being regulated by CSTB activity in a biological context; effects of decreased CSTB activity in EPM1 pathogenesis may be mediated by cathepsins through increased activity of cathepsins S and L PMID: 12452481
  32. Prefibrillar oligomers/aggregates of stefin B also increase the surface pressure at an air-water interface, i.e. they have amphipathic character and are surface seeking. PMID: 15955063
  33. These data show that cystatin B inhibits bone resorption by down-regulating intracellular cathepsin K activity despite increased osteoclast survival. PMID: 16321512
  34. Study shows that copper binding by stefin B inhibits the amyloid fibril formation and, to a lesser degree, the initial aggregation. PMID: 16939620
  35. Several alternatively spliced CSTB isoforms were identified in patients with progressive myoclonus epilepsy of Unverricht-Lundborg type . PMID: 17003839
  36. Results describe the influence of pH and trifluoroethanol on amyloid fibril growth and morphology from human stefin B. PMID: 17701471
  37. cystatin B in vivo has a polymeric structure sensitive to the redox environment and that overexpression of the protein generates aggregates. PMID: 17920138
  38. CSTB is specifically overexpressed in most HCCs and is also elevated in the serum of a large proportion of HCC patients PMID: 18281540
  39. Data show that wild-type stefin B and its Y31 isoform are able to form pores in planar lipid bilayers, whereas the G4R isoform destroys the bilayer by a non pore-forming process. PMID: 18397316
  40. The mechanism of amyloid-fibril formation by stefin B: temperature and protein concentration dependence of the rates;the observed kinetics follow the nucleation and growth behavior observed for many other amyloidogenic proteins. PMID: 18636508
  41. potential role for CSTB in HIV replication in placental macrophages PMID: 18951626
  42. cystatin B interacts with STAT-1 and the levels of STAT-1 tyrosine phosphorylation (but not serine phosphorylation) between uninfected and HIV-infected PM and MDM are differentially regulated. PMID: 19342095


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Proteins are sensitive to heat, and freeze-drying can preserve the activity of the majority of proteins. It improves protein stability, extends storage time, and reduces shipping costs. However, freeze-drying can also lead to the loss of the active portion of the protein and cause aggregation and denaturation issues. Nonetheless, these adverse effects can be minimized by incorporating protective agents such as stabilizers, additives, and excipients, and by carefully controlling various lyophilization conditions.

Commonly used protectant include saccharides, polyols, polymers, surfactants, some proteins and amino acids etc. We usually add 8% (mass ratio by volume) of trehalose and mannitol as lyoprotectant. Trehalose can significantly prevent the alter of the protein secondary structure, the extension and aggregation of proteins during freeze-drying process; mannitol is also a universal applied protectant and fillers, which can reduce the aggregation of certain proteins after lyophilization.

Our protein products do not contain carrier protein or other additives (such as bovine serum albumin (BSA), human serum albumin (HSA) and sucrose, etc., and when lyophilized with the solution with the lowest salt content, they often cannot form A white grid structure, but a small amount of protein is deposited in the tube during the freeze-drying process, forming a thin or invisible transparent protein layer.

Reminder: Before opening the tube cap, we recommend that you quickly centrifuge for 20-30 seconds in a small centrifuge, so that the protein attached to the tube cap or the tube wall can be aggregated at the bottom of the tube. Our quality control procedures ensure that each tube contains the correct amount of protein, and although sometimes you can't see the protein powder, the amount of protein in the tube is still very precise.

To learn more about how to properly dissolve the lyophilized recombinant protein, please visit Lyophilization FAQs.

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