Cathepsin
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A cathepsin (Union of two Greek words, kata-:down and hepsein:boil) is a cyseteine or aspartic protease, a type of protein that breaks apart other proteins, found in many types of cells including those in all animals. There are approximately a dozen members of this family, which are distinguished by their structure and which proteins they cleave. Most of the members become activated at the low pH found in lysosomes. Thus, the activity of this family lies almost entirely within those organelles.
Cathepsins have a vital role in mammalian cellular turnover, e.g. bone resorption. They degrade polypeptides and are distinguished by their substrate specificites.
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[edit] Clinical significance
Cathepsins have been implicated in:
- Cancer[1]
- Stroke[2]
- Alzheimer's disease,
- Arthritis[3]
- Ebola, Cathepsin L and to a lesser extent cathepsin B have been found to be necessary for the virus to enter host cells.
- COPD
Cathepsin A::Deficiencies in this protein are linked to multiple forms of galactosialidosis. The cathepsin A activity in lysates of metastatic lesions of malignant melanoma is significantly higher than in primary focus lysates. Cathepsin A increased in muscles moderately affected by muscular dystrophy and denervating diseases.
Cathepsin B:: seems to actually break down the proteins which cause amyloid plaque, the root of Alzheimer's symptoms, and may even be a pivotal part of the natural defense against this disease used by people who do not get it. Over expression of the encoded protein, which is a member of the peptidase C1 family, has been associated with esophageal adenocarcinoma and other tumors. Cathepsin B has also been implicated in the progression of various human tumors including ovarian cancer. Cathepsin B is also involved in apoptosis as well as degradation of myofibrillar proteins in myocardial infarction.
[edit] History
The earliest record of "cathepsin" found in PubMed is from the Journal of Biological Chemistry in 1949.[4]
However, references within this article indicate that they were first identified and named around the turn of the 20th century. Much of this earlier work was done in the laboratory of Max Bergmann, who spent the first several decades of the century defining these proteases. [5]
[edit] References
- ^ Nomura and Katunuma. Involvement of cathepsins in the invasion, metastasis and proliferation of cancer cells. J Med Invest. 2005 Feb;52(1-2):1-9. Review.
- ^ Lipton. Ischemic cell death in brain neurons. Physiol Rev. 1999 Oct;79(4):1431-568.
- ^ Pham. Immunity. 2005 Jun
- ^ Maver and Greco. The hydrolysis of nucleoproteins by cathepsins from calf thymus. J Biol Chem. 1949 Dec;181(2):853-60.
- ^ Bergmann and Fruton. Science 1936; 84(2169):89-90.
[edit] External links
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