کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
9882250 1536550 2005 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Cathepsin X binds to cell surface heparan sulfate proteoglycans
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Cathepsin X binds to cell surface heparan sulfate proteoglycans
چکیده انگلیسی
Glycosaminoglycans have been shown to be important regulators of activity of several papain-like cathepsins. Binding of glycosaminoglycans to cathepsins thus directly affects catalytic activity, stability or the rate of autocatalytic activation of cathepsins. The interaction between cathepsin X and heparin has been revealed by affinity chromatography using heparin-Sepharose. Conformational changes were observed to accompany heparin-cathepsin X interaction by far UV-circular dichroism at both acidic (4.5) and neutral (7.4) pH. These conformational changes promoted a 4-fold increase in the dissociation constant of the enzyme-substrate interaction and increased 2.6-fold the kcat value also. The interaction between cathepsin X and heparin or heparan sulfate is specific since dermatan sulfate, chondroitin sulfate, and hyaluronic acid had no effect on the cathepsin X activity. Using flow cytometry cathepsin X was shown to bind cell surface heparan sulfate proteoglycans in wild-type CHO cells but not in CHO-745 cells, which are deficient in glycosaminoglycan synthesis. Moreover, fluorescently labeled cathepsin X was shown by confocal microscopy to be endocytosed by wild-type CHO cells, but not by CHO-745 cells. These results demonstrate the existence of an endocytosis mechanism of cathepsin X by the CHO cells dependent on heparan sulfate proteoglycans present at the cell surface, thus strongly suggesting that heparan sulfate proteoglycans can regulate the cellular trafficking and the enzymatic activity of cathepsin X.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Archives of Biochemistry and Biophysics - Volume 436, Issue 2, 15 April 2005, Pages 323-332
نویسندگان
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