CTSB Research Reagents

What is CTSB?

Cathepsin B (CTSB) is a lysosomal endo- and exopeptidase in humans that is encoded by the CTSB gene. CTSB belongs to papain superfamily. It is originally synthesized as an inactive pre-procathepsin B, which matures via multiple procedures, including the co-translational removal of the pre-peptide, translocation to Golgi-apparatus for the cleavage of the pro-part, and the glycosylation of the mature form. The mature CTSB is transported to the lysosome through the M6P (mannose-6-phosphate). It is widely expressed in various tissues and cells, including in the brain.

What is the feature of the CTSB structure?

CTSB is bilobal in shape, with a catalytic site located at the interface between the two lobes. The catalytic region is a triad composed of the amino acids cysteine, histidine, and aspartic acid, and the interaction between cysteine on the left lobe and histidine on the right lobe catalyzes peptide bond cleavage. Different from other cathepsins, CTSB contains an 18 amino acid occluding loop lying between Pro107 and Asp124. Two salt bridges between the occluding and the mature enzyme partially block the substrate-binding cleft, thus promoting its peptidyldipeptidase activity.

What is the function of the CTSB?

In terms of coronavirus entry into the host cell, CTSB facilitates the activation of spike glycoprotein in the endosomal pathway.

As a lysosomal protease, CTSB is involved in several cellular degradation processes such as the degradation of protein & extracellular matrix, regulatory mechanisms, apoptosis, autophagy, and antigen representation. CTSB is also implicated in the pathology of chronic inflammatory diseases of airways and joints, cancer, and pancreatitis. CTSB has been proposed as a potentially effective biomarker for various cancers. Overexpression of CTSB is correlated with invasive and metastatic cancers. Recent studies show that CTSB executes other cellular programs such as controlling tumor growth, migration, invasion, angiogenesis, and metastases development. Moreover, the level of CTSB transcription and expression is positively correlated with the prognosis of the tumor.

Hot products of CTSB:

Recombinant Human Cathepsin B (CTSB), partial (Active) (C-terminal 6xHis-tagged) (CSB-AP005381HU)

Recombinant Human Cathepsin B (CTSB), partial (N-terminal GST-tagged) (CSB-EP006185HU1)

CTSB Antibody (ELISA, WB, IHC, IF) (CSB-PA06974A0Rb)

Human cathepsin B (CTSB) ELISA kit (CSB-E13450h)

The following CTSB reagents supplied by CUSABIO are manufactured under a strict quality control system. Multiple applications have been validated and solid technical support is offered.

CTSB Antibodies

CTSB Antibodies for Homo sapiens (Human)

CTSB Proteins

CTSB Proteins for Ovis aries (Sheep)

CTSB Proteins for Mus musculus (Mouse)

CTSB Proteins for Gallus gallus (Chicken)

CTSB Proteins for Rattus norvegicus (Rat)

CTSB Proteins for Homo sapiens (Human)

CTSB Proteins for Bos taurus (Bovine)

CTSB Proteins for Sus scrofa (Pig)

CTSB Proteins for Coturnix japonica (Japanese quail) (Coturnix coturnix japonica)

CTSB Proteins for Dictyostelium discoideum (Slime mold)

CTSB Proteins for Pongo abelii (Sumatran orangutan) (Pongo pygmaeus abelii)

CTSB Proteins for Macaca fascicularis (Crab-eating macaque) (Cynomolgus monkey)


CTSB ELISA Kit for Mus musculus (Mouse)

CTSB ELISA Kit for Rattus norvegicus (Rat)

CTSB ELISA Kit for Homo sapiens (Human)

CTSB Background

Cathepsin B (CTSB) is a lysosomal cysteine protease of the papain family [1] and is synthesized on the rough endoplasmic reticulum as a 339-amino acid preproenzyme [2]. Pro-cathepsin B is transported to the Golgi apparatus and then is processed into cathepsin B. CTSB has both endopeptidase and exopeptidase activity [3]. As an endopeptidase, CTSB is responsible for the cleavage of the S2-P2 specificity protein/peptide substrate [4]. While CTSB can cleave two amino acids (dipeptide) from the C-terminal of a polypeptide substrate as an exopeptidase [5]. Under normal physiologic conditions, active CTSB is localized in lysosomal and mainly takes part in the routine turnover of both intracellular and extracellular proteins, thus maintaining metabolic homeostatisis [6]. CTSB also mediates the regulation of pro-hormone & pro-enzyme activation, antigen processing, inflammatory responses against antigens, tissue remodeling, and apoptosis [1][7][8]. In response to certain signals, CTSB and other cathepsins are released from the lysosomes into the cytoplasm where they trigger apoptosis through the promotion of the activation of caspases or the release of proapoptotic factors from the mitochondria [9][10]. CTSB can also cleave Bid to produce the active truncated Bid (tBid) [11], just like the proteolysis of Bid by caspase 8 early during apoptosis. And CTSB also degrades the anti-apoptotic protein Bcl-xl. Besides, overexpression CTSB is associated with invasive and metastatic cancers [12]. The upregulation of CTSB expression can predict poor prognosis in several tumors such as ovarian carcinoma [13] and colon carcinoma [14].

[1] Mort JS, Buttle DJ Cathepsin B [J]. Int J Biochem Cell Biol. 1997 May; 29(5):715-20.
[2] Kirschke H, Barrett AJ, Rawlings ND Proteinases 1: lysosomal cysteine proteinases [J]. Protein Profile. 1995; 2(14):1581-643.
[3] Musil D, Zucic D, et al. The refined 2.15 A X-ray crystal structure of human liver cathepsin B: the structural basis for its specificity [J]. EMBO J. 1991 Sep; 10(9):2321-30.
[4] Hasnain S, Hirama T, et al. Characterization of cathepsin B specificity by site-directed mutagenesis. Importance of Glu245 in the S2-P2 specificity for arginine and its role in transition state stabilization [J]. J Biol Chem. 1993 Jan 5; 268(1):235-40.
[5] Cotrin SS, Puzer L, et al. Positional-scanning combinatorial libraries of fluorescence resonance energy transfer peptides to define substrate specificity of carboxydipeptidases: assays with human cathepsin B [J]. Anal Biochem. 2004 Dec 15; 335(2):244-52.
[6] Dora Cavallo-Medved,1 Kamiar Moin, et al. Cathepsin B. Basis Sequence: Mouse [J]. AFCS Nat Mol Pages. 2011; 2011: A000508.
[7] Reiser J, Adair B, Reinheckel T Specialized roles for cysteine cathepsins in health and disease [J]. J Clin Invest. 2010 Oct; 120(10):3421-31.
[8] Linke M, Jordans S, et al. Thyroid-stimulating hormone upregulates secretion of cathepsin B from thyroid epithelial cells [J]. Biol Chem. 2002 May; 383(5):773-84.
[9] Chwieralski CE, Welte T, et al. Cathepsin-regulated apoptosis [J]. Apoptosis 2006; 11: 143-149.
[10] Guicciardi ME, Deussing J, et al. Cathepsin B contributes to TNF-α-mediated hepatocyte apoptosis by promoting mitochondrial release of cytochrome c [J]. J Clin Invest 2000; 106: 1127-11378.
[11] Cirman T, Oresić K, et al. Selective disruption of lysosomes in HeLa cells triggers apoptosis mediated by cleavage of Bid by multiple papain-like lysosomal cathepsins [J]. J Biol Chem 2004; 279: 3578-3587.
[12] Roshy S, Sloane BF, Moin K Pericellular cathepsin B, and malignant progression [J]. Cancer Metastasis Rev. 2003 Jun-Sep; 22(2-3):271-86.
[13] Scorilas A, Fotiou S, et al. Determination of cathepsin B expression may offer additional prognostic information for ovarian cancer patients [J]. Biol Chem. 2002 Jul-Aug; 383(7-8):1297-303
[14] Campo E, Muñoz J, et al. Cathepsin B expression in colorectal carcinomas correlates with tumor progression and shortened patient survival [J]. Am J Pathol. 1994 Aug; 145(2):301-9.

Call us
301-363-4651 (Available 9 a.m. to 5 p.m. CST from Monday to Friday)
7505 Fannin St Ste 610-322 Houston, TX 77054, USA
Join Us with

Subscribe newsletter

Leave a message

© 2007-2023 CUSABIO TECHNOLOGY LLC All rights reserved. 鄂ICP备15011166号-1