INACTIVATOR OF THIRD COMPONENT OF COMPLEMENT AS AN INHIBITOR IN PROPERDIN PATHWAY
INACTIVATOR OF THIRD COMPONENT OF COMPLEMENT AS AN INHIBITOR IN PROPERDIN PATHWAY
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DOI：
10.1073/pnas.69.10.2910
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发表时间：
1972-01-01
影响因子：
11.1
通讯作者：
LACHMANN, PJ
中科院分区：
文献类型：
--
作者：
ALPER, CA;ROSEN, FS;LACHMANN, PJ
已经获得的证据表明，已知调节经典补体激活的单一蛋白质也在备解素或替代补体途径中充当抑制剂。从人血清中提取的一种高纯度补体第三组分（C3）灭活剂抑制备解素系统中富含甘氨酸的β-糖蛋白酶对B因子（富含甘氨酸的β-糖蛋白）的蛋白水解。这种抑制是通过富含甘氨酸的β-糖蛋白酶活性的酶促破坏实现的。C3的主要片段C3 b是C3灭活剂的唯一已知底物，其阻断C3灭活剂对富含甘氨酸的β-糖蛋白酶的破坏。因此，在其对porperdin途径的抑制中，C3灭活剂破坏富含甘氨酸的β-糖蛋白酶的活性形式和参与该酶的酶原形式（富含原甘氨酸的β-糖蛋白酶）转化为其活性形式的蛋白质。C3灭活蛋白缺乏纯合子患者感染易感性的增加证明了该蛋白的生物学意义。
Evidence has been obtained that a single protein, known to modulate classical complement activation, also acts as an inhibitor in the properdin or alternate complement pathway. A highly purified inactivator of the third component of complement (C3) from human serum inhibited the proteolysis of Factor B in the properdin system (glycine-rich β-glycoprotein) by glycine-rich β-glycoproteinase. The inhibition was by the enzymatic destruction of glycine-rich β-glycoproteinase activity. The major fragment of C3, C3b, which is the only known substrate of the C3 inactivator, blocked the destruction of glycine-rich β-glycoproteinase by the C3 inactivator. Thus, in its inhibition of the porperdin pathway, the C3 inactivator destroys both the active form of glycine-rich β-glycoproteinase and a protein involved in the conversion of the zymogen form of this enzyme (proglycine-rich β-glycoproteinase) to its active form. The increased susceptibility to infections in a patient homozygous for deficiency of the C3 inactivator demonstrates the biologic significance of this protein.