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The acid phosphatase positive organelles of the Giardia lamblia trophozoite contain a membrane bound cathepsin C activity
Author(s) -
Thirion Jacqueline,
Wattiaux Robert,
Jadot Michel
Publication year - 2003
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1016/s0248-4900(03)00006-6
Subject(s) - giardia lamblia , biology , biochemistry , organelle , enzyme , lysosome , cathepsin d , cathepsin l , cathepsin , giardia , acid phosphatase , cathepsin c , microbiology and biotechnology
We found a dipeptidyl aminopeptidase activity in the parasitic protozoan Giardia lamblia with properties similar to the lysosomal cathepsin C of rat‐liver lysosomes. Subcellular fractionation of this parasite indicated that the cathepsin C activity is located in organelles not distinguishable from the ones containing acid phosphatase, a known marker enzyme of Giardia lysosome‐like peripheral vesicles. Contrary to the rat lysosomal enzyme, Giardia cathepsin C behaved like a membrane protein. Moreover, the enzyme was not solubilized by Triton X‐100 or Triton X‐100/SDS at 0 °C but could be substantially solubilized by octylglucoside, Triton X‐100 at 37 °C or by a pretreatment with the cholesterol complexing agent β‐cyclodextrin before the Triton/SDS treatment carried out at 0 °C. These observations suggest that binding/anchorage of this enzyme to membranes occurs in cholesterol‐rich microdomains.