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标题：N-linked glycosylation of macrophage-derived PAF-AH is a major determinant of enzyme association with plasma HDL
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作者：Alexandros D. Tselepis ; Sonia-Athena P. Karabina ; Dominique Stengel 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2001
卷号：42
期号：10
页码：1645-1654
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：Human plasma PAF-AH (platelet-activating factor-acetylhydrolase) is a Ca²⁺-independent phospholipase A₂ of hematopoietic origin associated with LDL and HDL; it degrades PAF and oxidizes phospholipids. We show that human macrophages synthesize PAF-AH as a premedial Golgi precursor containing high mannose N-linked glycans. Secreted PAF-AH possesses a molecular mass of ~55 kDa and contains mature N-linked glycans. Secreted PAF-AH activity (90 ± 4% of the total) bound to a wheat germ lectin column and could be eluted with N -acetylglucosamine, whereas digestion with N -acetylneuraminidase II completely abolished enzyme absorption. Tunicamycin significantly reduced cell-associated PAF-AH activity and inhibited enzyme secretion; but it did not alter the ratio of secreted to cell-associated enzyme (1.8 at 6 h and 3.1 at 24 h), suggesting that glycosylation is not essential for PAF-AH secretion. Digestion of cell-associated PAF-AH or secreted PAF-AH with peptide N -glycosidase F affected neither catalytic activity nor its resistance to proteolysis with trypsin or proteinase K; in addition, it did not affect PAF-AH association with LDL, but significantly increased its association with HDL. We suggest that macrophage-derived PAF-AH contains heterogeneous asparagine-conjugated sugar chain(s) involving sialic acid, which hinders its association with HDL but does not influence the secretion, catalytic activity, or resistance of PAF-AH to proteases. —Tselepis, A. D., S-A. P. Karabina, D. Stengel, R. Piédagnel, M. J. Chapman, and E. Ninio. N-linked glycosylation of macrophage-derived PAF-AH is a major determinant of enzyme association with plasma HDL. J. Lipid Res. 2001. 42: 1645–1654.
关键词：atherogenesis ; lipoproteins ; macrophages