A GLYCAN-PHOSPHATIDYLINOSITOL SPECIFIC PHOSPHOLIPASE-D IN HUMAN-SERUM
A GLYCAN-PHOSPHATIDYLINOSITOL SPECIFIC PHOSPHOLIPASE-D IN HUMAN-SERUM
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DOI：
10.1126/science.2443973
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发表时间：
1987-10-02
期刊：
影响因子：
56.9
通讯作者：
NUSSENZWEIG, V
中科院分区：
文献类型：
--
作者：
DAVITZ, MA;HERELD, D;NUSSENZWEIG, V
一组患者锚定的细胞磷脂酰肌醇（PI）最近已被确定。这类新的膜锚的意义尚不清楚;一种可能性是它促进了磷脂酶释放分子。事实上，磷脂酶C酶的复杂的羧基末端糖脂的这些蛋白质已被分离出非洲锥虫和肝细胞质膜。本研究报告发现的聚糖PI特异性磷脂酶D在人血清中，切割膜形式的变体表面糖蛋白的非洲锥虫和其糖脂前体，但不是磷脂酰乙醇胺，磷脂酰胆碱，或磷脂酰肌醇。衰变加速因子，另一种PI锚定分子，也被酶切割，并从疏水蛋白转化为可溶性蛋白。该酶是Ca 2+依赖性的，热不稳定的，不受丝氨酸蛋白酶抑制剂苯甲基磺酰氟的影响。其功能尚不清楚，但目前的研究结果表明，它参与糖脂锚定膜蛋白的代谢。
A group of patients 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 Ca2+-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.