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-beta-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 V(max) (35%) without a significant change in K(m). 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.
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Food Res Int
February 2025
Research Center of Grain and Oil Functionalized Processing in Universities of Shaanxi Province, College of Food Science and Engineering, Northwest A&F University, 22 Xinong Road, Yangling 712100, Shaanxi, PR China. Electronic address:
Lipids are essential sources of carbon and energy during flaxseed germination; however, the dynamic changes in key lipid metabolites, pathways, and their locations remain unclear. This study revealed that oil bodies migrated from well-distributed locations to the cell wall between 0-2 d, with cell contours gradually blurring during 2-3 d, initiating the germination process. Subsequently, the order of oil body migration was leaf > stem > root during 4-7 d.
View Article and Find Full Text PDFTrends Cell Biol
January 2025
Division of Biochemistry, The Netherlands Cancer Institute, Amsterdam, The Netherlands. Electronic address:
Glycosylphosphatidylinositol (GPI)-anchored proteins (APs) regulate numerous biological processes through interaction with signaling effectors at the cell surface. As a unique feature, GPI-APs can be released from their anchors by multi-pass GPI-specific phospholipases (types A2, C, and D) to impact signaling networks, phenotype, and cell fate; however, many questions remain outstanding. Here, we discuss and expand our current understanding of the distinct GPI-specific phospholipases, their substrates, effector pathways, and emerging physiological roles, with a focus on the six-transmembrane ecto-phospholipases GDE2 (GDPD5) and GDE3 (GDPD2).
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January 2025
Department of Medicine, Michigan State University College of Human Medicine, East Lansing, Michigan, USA.
Disruption of extracellular pH and proton-sensing can profoundly impact cellular and protein functions, leading to developmental defects. To visualize changes in extracellular pH in the developing embryo, we generated a zebrafish transgenic line that ubiquitously expresses the ratiometric pH-sensitive fluorescent protein pHluorin2, tethered to the extracellular face of the plasma membrane using a glycosylphosphatidylinositol (GPI) anchor. Monitoring of pHluorin2 with ratiometric fluorescence revealed dynamic and discrete domains of extracellular acidification over the first 72 h of embryonic development.
View Article and Find Full Text PDFJ Carbohydr Chem
April 2024
Department of Chemistry, University of Florida, 214 Leigh Hall, Gainesville, FL 32611, USA.
Glycosylphosphatidylinositol (GPI) anchors contain a unique α-D-glucosamine-(1→6)--inositol [αGlcN(1,6)Ins] motif in their conserved core structure. To facilitate investigations of the functional roles of this structural motif, two GPI analogues containing unnatural βGlcN(1,6)Ins, instead of αGlcN(1,6)Ins, and an alkyne group at different positions of the GPI core were designed and synthesized. To this end, an orthogonally protected pseudopentasaccharide derivative of GPIs with the βGlcN(1,6)Ins motif was convergently constructed via [3+2] glycosylation and used as the common intermediate to prepare both GPI analogues by streamlined synthetic protocols.
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January 2025
Xiamen Key Laboratory of Brain Center, The First Affiliated Hospital of Xiamen University, and Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China.
Mutations in the synaptic protein MAM domain containing glycosylphosphatidylinositol anchor 2 (MDGA2) have been associated with autism spectrum disorder (ASD). Therefore, elucidating the regulatory mechanisms of MDGA2 can help develop effective treatments for ASD. Liquid chromatography-tandem mass spectrometry was carried out to identify proteins interacting with the extracellular domain of RPS23RG1 and with MDGA2, followed by co-immunoprecipitation assays to confirm protein-protein interactions.
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