A Glycan-Phosphatidylinositol-Specific Phospholipase D in Human Serum

A group of proteins anchored to the cell by phosphatidylinositol (PI) has recently been identified. The significance of this new class of membrane anchor is unknown; one possibility is that it facilitates release of the molecule by phospholipases. In fact, phospholipase C enzymes specific for the co...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 1987-10, Vol.238 (4823), p.81-84
Main Authors: Davitz, Michael A., Hereld, Dale, Shak, Steve, Krakow, Jessica, Englund, Paul T., Nussenzweig, Victor
Format: Article
Language:English
Subjects:
Antibodies
Biochemistry
Biological and medical sciences
CD55 Antigens
Cell membranes
Cell membranes. Ionic channels. Membrane pores
Cell structures and functions
Enzymes
Epithelial cells
Fundamental and applied biological sciences. Psychology
Glycolipids
Glycolipids - metabolism
HeLa cells
Humans
Lipid research
Lipids
Medical research
Membrane Proteins - metabolism
Memory interference
Molecular and cellular biology
Phosphatidic acids
Phosphatidylinositols - metabolism
Phospholipase D - antagonists & inhibitors
Phospholipase D - blood
Phospholipases
Phospholipases - blood
Proteins
Radioactive decay
Solubility
Substrate Specificity
Variant Surface Glycoproteins, Trypanosoma - metabolism
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Summary:A group of proteins anchored to the cell by phosphatidylinositol (PI) has recently been identified. The significance of this new class of membrane anchor is unknown; one possibility is that it facilitates release of the molecule by phospholipases. In fact, phospholipase C enzymes specific for the complex carboxyl-terminal glycolipids of these proteins have been isolated from African trypanosomes and from hepatocyte plasma membranes. This study reports the discovery of a glycan-PI-specific phospholipase D in human serum that cleaves both the membrane form of the variant surface glycoprotein of African trypanosomes and its glycolipid precursor, but not phosphatidylethanolamine, phosphatidylcholine, or phosphatidylinositol. Decay-accelerating factor, another PI-anchored molecule, is also cleaved by the enzyme and converted from a hydrophobic to a soluble protein. The enzyme is Ca$^{2+}$-dependent, heat labile, and not affected by the inhibitor of serine proteases, phenylmethylsulfonylfluoride. Its function is not known, but the present findings indicate that it participates in the metabolism of glycolipid-anchored membrane proteins.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.2443973