PROPERDIN, THE TERMINAL COMPLEMENT COMPONENTS, THROMBOSPONDIN AND THE CIRCUMSPOROZOITE PROTEIN OF MALARIA PARASITES CONTAIN SIMILAR SEQUENCE MOTIFS
PROPERDIN, THE TERMINAL COMPLEMENT COMPONENTS, THROMBOSPONDIN AND THE CIRCUMSPOROZOITE PROTEIN OF MALARIA PARASITES CONTAIN SIMILAR SEQUENCE MOTIFS
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DOI：
10.1038/335082a0
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发表时间：
1988-09-01
期刊：
影响因子：
64.8
通讯作者：
REID, KBM
中科院分区：
文献类型：
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作者：
GOUNDIS, D;REID, KBM
备解素是一种血浆糖蛋白，它稳定补体系统1，2的替代途径的C3bnBb‘酶复合体。不同于经典途径，C1q与免疫复合体中Ig G或Ig M抗体的Fc区相互作用，替代途径可以通过C3b与外来组织表面的结合直接激活。稳定的C3bnBbP’复合体激活C3和C5，导致异物(通过C3b)被调理，并组装(通过C5b)靶细胞上的膜攻击复合体。因此，在天然和获得性感染1，4中，备解素大大增强了补体介导的清除和失活机制。本文表明，备解素的初级氨基酸序列主要由6个重复的基序组成，每个基序由60个氨基酸组成，在疟疾寄生虫的环子孢子蛋白5和补体9的膜攻击成分的区域中发现了相似的序列。这些相似性可能为了解寄生虫逃避补体介导的宿主防御的机制提供了洞察力。
Properdin is a plasma glycoprotein which stabilizes the C3bnBb¯ enzyme complex of the alternative pathway of the complement system1,2. Unlike the classical pathway, which is initiated by interaction of C1q with the Fc regions of IgG or IgM antibodies in immune complexes, the alternative pathway can be directly activated via binding of C3b to surfaces of foreign organisms3,4. The stabilized C3bnBbP¯ complex activates components C3 and C5 resulting in opsonization of foreign material (via C3b) and assembly of the membrane attack complex (via C5b) on target cells. Therefore properdin greatly enhances complement-mediated clearance and inactivation mechanisms in both natural and acquired resistance to infection1,4. This paper shows that the primary amino acid sequence of properdin is composed mainly of six repeating motifs, each of ∼60 amino acids, and that similar sequences are found in thrombospondin5, the circumsporozoite protein of malaria parasites6–8and regions of the membrane-attack components of complement9. These similarities may provide insight into the mechanisms by which parasites avoid host defences mediated by complement.