Increased activity of goat liver plasma membrane alkaline phosphatase upon release by phosphatidylinositol-specific phospholipase C.
Loading...
Date
2014-08
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Mammalian alkaline phosphatase (ALP) is attached to the plasma membrane by a unique glycosylphosphatidylinositol (GPI) anchor. The influence of such a complex anchoring device on the enzyme function is not fully understood. Here, we report the effect of cleavage of the GPI anchor on the activity of goat liver plasma membrane ALP (GLPM-ALP). Phosphatidylinositol-specific phospholipase C (PI-PLC) purified from Bacillus cereus was used for the cleavage of the GPI anchor (delipidation) and hence for release of ALP from the membrane. Detergents — octyl-β-D-glucopyranoside (OG) and triton X100 (TX100) were also used for solubilization of ALP from the membrane. Resistance to solubilization by TX100 suggested the association of GPI-ALP with lipid rafts. Solubilization of GLPM-ALP with OG had no effect on the enzyme activity; however, delipidation with PI-PLC resulted in enhanced ALP activity. Kinetic analysis showed catalytic activation of PI-PLC-treated GLPM-ALP with an increase in Vmax (35%) without a significant change in Km. Moreover, this change in Vmax was observed to be independent of pH and buffer. The results suggested the implication of GPI anchor in modulating the catalytic property of GLPM-ALP, thus indicating the role of this special anchoring structure in the enzyme regulation.
Description
Keywords
Alkaline phosphatase, Delipidation, Glycosylphosphatidylinositol anchor, Goat liver plasma membrane, Increased activity, Phosphatidylinositol-specific phospholipase C
Citation
Kothekar Deepali, Bandivdekar Atmaram, Dasgupta Debjani. Increased activity of goat liver plasma membrane alkaline phosphatase upon release by phosphatidylinositol-specific phospholipase C. Indian Journal of Biochemistry & Biophysics. 2014 Aug; 51(4): 263-270.