Placental anticoagulant proteins: isolation and comparative characterization four members of the lipocortin family.
Placental anticoagulant proteins: isolation and comparative characterization four members of the lipocortin family.
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DOI：
10.1021/bi00417a011
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发表时间：
1988-08
期刊：
影响因子：
2.9
通讯作者：
J. Tait;M. Sakata;B. McMullen;C. Miao;T. Funakoshi;L. Hendrickson;K. Fujikawa
中科院分区：
文献类型：
--
作者：
J. Tait;M. Sakata;B. McMullen;C. Miao;T. Funakoshi;L. Hendrickson;K. Fujikawa
此前，我们分离并鉴定了胎盘抗凝蛋白(PAP或PAP-I)，它是一种依赖于钙离子的磷脂结合蛋白[Funakoshi等人]。(1987)生物化学26,5572]和脂皮质素家族的成员[Funakoshi等人。(1987)生物化学26,8087]。在这项研究中，另外三种抗凝蛋白(PAP-II、PAP-III和PAP-IV)被同时从5 mM乙二胺四乙酸存在下制备的人胎盘匀浆中分离出来。PAP-I、PAP-II、PAP-III和PAP-IV的等电点分别为4.8、6.1、5.9和8.1，表观分子量分别为32,000、33,000、34,000和34,500。这些蛋白质的溴化氰片段的氨基酸序列表明，PAP-III是以前未被识别的Lipocortin家族的成员，而PAP-II可能是猪蛋白II的人类同源物，PAP-IV是在氨基端附近截短的Lipocortin II的衍生物。比较研究表明，所有四种蛋白质都能抑制凝血和磷脂酶A2的活性，其效力与它们对阴离子磷脂小泡的相对亲和力一致。然而，PAP-IV与磷脂微囊的结合强度约为PAP-I的160倍，而PAP-II和PAP-III的结合强度仅为PAP-I的2倍和3倍。这些结果使人类胎盘中已知的脂皮质素样蛋白的数量增加到6个。观察到的磷脂结合的差异可能表明脂皮质素家族成员之间的功能差异，尽管它们在结构上有相当大的相似之处。
Previously we isolated and characterized a placental anticoagulant protein (PAP or PAP-I), which is a Ca2+-dependent phospholipid binding protein [Funakoshi et al. (1987) Biochemistry 26, 5572] and a member of the lipocortin family [Funakoshi et al. (1987) Biochemistry 26, 8087]. In this study, three additional anticoagulant proteins (PAP-II, PAP-III, and PAP-IV) were simultaneously isolated from human placental homogenates prepared in the presence of 5 mM ethylenediaminetetraacetic acid. The isoelectric points of PAP-I, PAP-II, PAP-III, and PAP-IV were 4.8, 6.1, 5.9, and 8.1, respectively, and their apparent molecular weights were 32,000, 33,000, 34,000, and 34,500, respectively. Amino acid sequences of cyanogen bromide fragments of these proteins showed that PAP-III was a previously unrecognized member of the lipocortin family, while PAP-II was probably the human homologue of porcine protein II and PAP-IV was a derivative of lipocortin II truncated near the amino terminus. Comparative studies showed that all four proteins inhibited blood clotting and phospholipase A2 activity with potencies consistent with their measured relative affinities for anionic phospholipid vesicles. However, PAP-IV bound to phospholipid vesicles approximately 160-fold more weakly than PAP-I, while PAP-II and PAP-III bound only 2-fold and 3-fold more weakly. These results increase to six the number of lipocortin-like proteins known to exist in human placenta. The observed differences in phospholipid binding may indicate functional differences among the members of the lipocortin family despite their considerable structural similarities.