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Cathepsin E (CTSE) is an intracellular aspartic protease that was originally identified as a cathepsin D-like acid protease. CTSE and CTSD have similar substrate specificities and CTSE is active in acidic conditions in a pH range from 2.5 to 5.5. In vitro experiments have identified several CTSE substrates including the insulin beta chain, neurokinin, and FGF. Although the function of CTSE is not completely understood, it has been implicated in several physiological and pathological processes. CTSE is required for antigen presentation on class II MHC molecules and subsequently, CTSE-deficient mice have increased susceptibility to bacterial infections. CTSE-deficient macrophages also show abnormalities, such as autophagy. Like many other cathepsins, CTSE has emerged as a therapy target for cancers such as pancreatic ductal adenocarcinoma (PDAC). Additionally to PDAC, CTSE is also overexpressed in gastric carcinomas and cervical and lung adenocarcinomas. The possible involvement of CTSE in neurodegeneration has also been reported.Product Details
- Mouse Cathepsin E, amino acids (Gln19-Pro397) (Accession#: P70269), with a C-terminal 10His tag was expressed in 293E cells.
- Molecular Mass
- The 389 amino acid recombinant protein has a predicted molecular mass of approximately 42.3 kD. The protein migrates at approximately 45 kD in DTT-reducing conditions and at approximately 90 kD by SDS-PAGE. The predicted N-terminal amino acid is Gln.
- >95%, as determined by Coomassie stained SDS-PAGE.
- 0.22 µm filtered protein solution is in 1x PBS.
- Endotoxin Level
- Less than 0.01 ng per µg cytokine as determined by the LAL method.
- 10 and 25 µg sizes are bottled at 200 µg/mL. 100 µg size and larger sizes are lot-specific and bottled at the concentration indicated on the vial (please contact technical support for concentration, or use our Lookup tool if you have a lot number.) Please note, new lots of the 100 µg size will be lot-specific and may differ from previous lots that had a fixed concentration.
- Storage & Handling
- Unopened vial can be stored at -70°C for six months. For maximum results, quick spin vial prior to opening. Avoid repeated freeze/thaw cycles.
- After autoactivation, CTSE activity is determined by its ability to cleave the fluorogenic peptide substrate, Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2. The specific activity is > 5500 pmol/min/µg.
- Application Notes
Activation Protocol for Mouse Cathepsin E
Step 1: Dilute the recombinant mouse CTSE to 1 µg/mL in assay buffer (50 mM NaOAc, 0.1 M NaCl, pH 3.5) and incubate the protein at room temperature for 15 minutes to activate CTSE. After activation, dilute the activated CTSE to 40 ng/ml using the assay buffer.
Step 2: Dilute the fluorogenic peptide substrate (Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2) to 40 µM using the assay buffer.
Step 3: Perform the assay in a black 96-well flat-bottom plate. Add 50 µl of the diluted, activated CTSE (40ng/ml) to a well and start the reaction by adding 50 µl of 40 µM substrate. The assay is read on a fluorometer at excitation and emission wavelengths of 320 nm and 405 nm.
This protein is in the latent form and needs to be activated for bioassay.
BioLegend carrier-free recombinant proteins provided in liquid format are shipped on blue-ice. Our comparison testing data indicates that when handled and stored as recommended, the liquid format has equal or better stability and shelf-life compared to commercially available lyophilized proteins after reconstitution. Our liquid proteins are verified in-house to maintain activity after shipping on blue ice and are backed by our 100% satisfaction guarantee. If you have any concerns, contact us at firstname.lastname@example.org.
- Disulfide-linked dimer.
CTSE is mainly expressed by immune cells including macrophages, activated B lymphocytes, microglia, and dendritic cells. Mature form of CTSE is localized mainly in endosomal compartments; the inactive proform exists in ER and Golgi.
- CTSE expression is negatively regulated by the MHC Class II transactivator.
- Substrate P, Neurokinin A, Eledoisin, Kassinin, FGF, b-endorphin, porcine renin substrate.
- Biology Area
- Apoptosis/Tumor Suppressors/Cell Death, Cell Biology, Neurodegeneration, Neuroscience, Neuroscience Cell Markers, Protein Trafficking and Clearance, Stem Cells
- Molecular Family
- Enzymes and Regulators, Lysosomal Markers
- Antigen References
1. Nishioku T, et al. 2002. J. Biol. Chem. 277:4816-4822.
2. Sastradipura D, et al. 1998. J. Neurochem. 70:2045-2056.
3. Presta M, et al. 2005. Cytokine Growth Factor Rev. 16:159-78.
4. Wiedlocha A, et al. 2008. Crit. Rev. Clin. Lab Sci. 45:91-135.
5. Saku T, et al. 1991. J. Biochem. 110:956-964.
6. Eser S, et al. 2011. Proc. Natl. Acad. Sci. USA 108:9945-9950.
7. Yasukochi A, et al. 2010. Biol. Chem. 391:947-958.
- Gene ID
- 13034 View all products for this Gene ID
- View information about Cathepsin E on UniProt.org
- Does specific activity of a recombinant protein vary between lots?
Specific activity will vary for each lot and for the type of experiment that is done to validate it, but all passed lots will have activity within the established ED50 range for the product and we guarantee that our products will have lot-to-lot consistency. Please conduct an experiment-specific validation to find the optimal ED50 for your system.
- Have your recombinants been tested for stability?
Our testing shows that the recombinant proteins are able to withstand room temperature for a week without losing activity. In addition the recombinant proteins were also found to withstand four cycles of freeze and thaw without losing activity.
- How do you convert activity as an ED50 in ng/ml to a specific activity in Units/mg?
- Use formula Specific activity (Units/mg) = 10e6/ ED50 (ng/mL)
- How does the activity of your recombinant proteins compare to competitors?
We quality control each and every lot of recombinant protein. Not only do we check its bioactivity, but we also compare it against other commercially available recombinant proteins. We make sure each recombinant protein’s activity is at least as good as or better than the competition’s. In order to provide you with the best possible product, we ensure that our testing process is rigorous and thorough. If you’re curious and eager to make the switch to BioLegend recombinants, contact your sales representative today!
- What is the specific activity or ED50 of my recombinant protein?
The specific activity range of the protein is indicated on the product datasheets. Because the exact activity values on a per unit basis can largely fluctuate depending on a number of factors, including the nature of the assay, cell density, age of cells/passage number, culture media used, and end user technique, the specific activity is best defined as a range and we guarantee the specific activity of all our lots will be within the range indicated on the datasheet. Please note this only applies to recombinants labeled for use in bioassays. ELISA standard recombinant proteins are not recommended for bioassay usage as they are not tested for these applications.