Cystatin B Explained

Cystatin-B is a protein that in humans is encoded by the CSTB gene.^{[1] [2]}

The cystatin superfamily encompasses proteins that contain multiple cystatin-like sequences. Some of the members are active cysteine protease inhibitors, while others have lost or perhaps never acquired this inhibitory activity. There are three inhibitory families in the superfamily, including the type 1 cystatins (stefins), type 2 cystatins and kininogens. This gene encodes a stefin that functions as an intracellular cysteine protease inhibitor. The protein is able to form a dimer stabilized by noncovalent forces, inhibiting papain and cathepsins L, H and B. The protein is thought to play a role in protecting against the proteases leaking from lysosomes. Evidence indicates that mutations in this gene are responsible for the primary defects in patients with Unverricht–Lundborg disease, a form of progressive myoclonic epilepsy (EPM1).^[2]

Interactions

Cystatin B has been shown to interact with Cathepsin B.^{[3] [4]}

Further reading

• Turk V, Bode W . The cystatins: protein inhibitors of cysteine proteinases. . FEBS Lett. . 285 . 2 . 213–9 . 1991 . 1855589 . 10.1016/0014-5793(91)80804-C . 40444629 .
• Järvinen M, Rinne A, Hopsu-Havu VK . Human cystatins in normal and diseased tissues--a review. . Acta Histochem. . 82 . 1 . 5–18 . 1988 . 3122506 . 10.1016/s0065-1281(87)80043-0.
• Brown WM, Dziegielewska KM . Friends and relations of the cystatin superfamily--new members and their evolution. . Protein Sci. . 6 . 1 . 5–12 . 1997 . 9007972 . 10.1002/pro.5560060102 . 2143511 .
• Kos J, Lah TT . Cysteine proteinases and their endogenous inhibitors: target proteins for prognosis, diagnosis and therapy in cancer (review). . Oncol. Rep. . 5 . 6 . 1349–61 . 1998 . 9769367 . 10.3892/or.5.6.1349.
• Stubbs MT, Laber B, Bode W . The refined 2.4 A X-ray crystal structure of recombinant human stefin B in complex with the cysteine proteinase papain: a novel type of proteinase inhibitor interaction. . EMBO J. . 9 . 6 . 1939–47 . 1990 . 2347312 . 10.1002/j.1460-2075.1990.tb08321.x. 551902 . etal.
• Jerala R, Trstenjak M, Lenarcic B, Turk V . Cloning a synthetic gene for human stefin B and its expression in E. coli. . FEBS Lett. . 239 . 1 . 41–4 . 1988 . 3053245 . 10.1016/0014-5793(88)80541-6 . 33859701 .
• Lenarcic B, Kos J, Dolenc I . Cathepsin D inactivates cysteine proteinase inhibitors, cystatins. . Biochem. Biophys. Res. Commun. . 154 . 2 . 765–72 . 1988 . 3261170 . 10.1016/0006-291X(88)90206-9 . etal.
• Ritonja A, Machleidt W, Barrett AJ . Amino acid sequence of the intracellular cysteine proteinase inhibitor cystatin B from human liver. . Biochem. Biophys. Res. Commun. . 131 . 3 . 1187–92 . 1985 . 3902020 . 10.1016/0006-291X(85)90216-5 .
• Spiess E, Brüning A, Gack S . Cathepsin B activity in human lung tumor cell lines: ultrastructural localization, pH sensitivity, and inhibitor status at the cellular level. . J. Histochem. Cytochem. . 42 . 7 . 917–29 . 1994 . 8014475 . 10.1177/42.7.8014475. 24509312 . etal.
• Lehesjoki AE, Koskiniemi M, Norio R . Localization of the EPM1 gene for progressive myoclonus epilepsy on chromosome 21: linkage disequilibrium allows high resolution mapping. . Hum. Mol. Genet. . 2 . 8 . 1229–34 . 1993 . 8104628 . 10.1093/hmg/2.8.1229 . etal.
• Pennacchio LA, Myers RM . Len A. Pennacchio . Isolation and characterization of the mouse cystatin B gene. . Genome Res. . 6 . 11 . 1103–9 . 1997 . 8938434 . 10.1101/gr.6.11.1103 . free .
• Lalioti MD, Mirotsou M, Buresi C . Identification of mutations in cystatin B, the gene responsible for the Unverricht-Lundborg type of progressive myoclonus epilepsy (EPM1). . Am. J. Hum. Genet. . 60 . 2 . 342–51 . 1997 . 9012407 . 1712389 . etal.
• Lafrenière RG, Rochefort DL, Chrétien N . Unstable insertion in the 5' flanking region of the cystatin B gene is the most common mutation in progressive myoclonus epilepsy type 1, EPM1. . Nat. Genet. . 15 . 3 . 298–302 . 1997 . 9054946 . 10.1038/ng0397-298 . 21180258 . etal.
• Virtaneva K, D'Amato E, Miao J . Unstable minisatellite expansion causing recessively inherited myoclonus epilepsy, EPM1. . Nat. Genet. . 15 . 4 . 393–6 . 1997 . 9090386 . 10.1038/ng0497-393 . 24971949 . etal.
• Bespalova IN, Adkins S, Pranzatelli M, Burmeister M . Novel cystatin B mutation and diagnostic PCR assay in an Unverricht-Lundborg progressive myoclonus epilepsy patient. . Am. J. Med. Genet. . 74 . 5 . 467–71 . 1997 . 9342192 . 10.1002/(SICI)1096-8628(19970919)74:5<467::AID-AJMG1>3.0.CO;2-L . 2027.42/38271 . free .

External links

• GeneReviews/NCBI/NIH/UW entry on Unverricht-Lundborg Disease or EPM1
• The MEROPS online database for peptidases and their inhibitors: I25.003
• PDBe-KB provides an overview of all the structure information available in the PDB for Human Cystatin-B

Notes and References

1. Pennacchio LA, Lehesjoki AE, Stone NE, Willour VL, Virtaneva K, Miao J, D'Amato E, Ramirez L, Faham M, Koskiniemi M, Warrington JA, Norio R, de la Chapelle A, Cox DR, Myers RM . Len A. Pennacchio . Mutations in the gene encoding cystatin B in progressive myoclonus epilepsy (EPM1) . Science . 271 . 5256 . 1731–4 . Apr 1996 . 8596935 . 10.1126/science.271.5256.1731 . 1996Sci...271.1731P . 84361089 .
2. Web site: Entrez Gene: CSTB cystatin B (stefin B).
3. Pavlova . Alona . Björk Ingemar . Sep 2003 . Grafting of features of cystatins C or B into the N-terminal region or second binding loop of cystatin A (stefin A) substantially enhances inhibition of cysteine proteinases . Biochemistry . 42 . 38 . 11326–33 . United States. 0006-2960. 14503883 . 10.1021/bi030119v .
4. Pol . E . Björk I . Sep 2001 . Role of the single cysteine residue, Cys 3, of human and bovine cystatin B (stefin B) in the inhibition of cysteine proteinases . Protein Sci. . 10 . 9 . 1729–38 . United States. 0961-8368. 11514663 . 10.1110/ps.11901 . 2253190 .