Porter R R
Ann Inst Pasteur Immunol (1985). 1985 Jan-Feb;136C(1):91-101. doi: 10.1016/s0769-2625(85)80042-8.
Genes coding for the complement proteins C2, C4A, C4B and factor B lie between HLA-D and HLA-B in HLA, the major histocompatibility complex in man. All the complement components are polymorphic, particularly C4, which has many alleles at each locus. The genetic complexity of C4 extends to the number of loci each of which may be deleted or duplicated on the chromosome. The different forms of C4 showed markedly different reactivities with small molecules and on haemolytic activity in the complement system. Surprisingly, amino acid sequences of the several allelic forms of C4 appear to be very similar, with less than 1% of residue positions being changed between alleles of C4A and C4B. These results may be relevant to the increased susceptibility to autoimmune disease which is associated with particular haplotypes of the HLA complex.
编码补体蛋白C2、C4A、C4B和B因子的基因位于人类主要组织相容性复合体HLA中HLA - D和HLA - B之间。所有补体成分都是多态性的，尤其是C4，每个基因座都有许多等位基因。C4的遗传复杂性还体现在每个基因座在染色体上可能缺失或重复的数量上。不同形式的C4在与小分子的反应以及补体系统中的溶血活性方面表现出明显不同。令人惊讶的是，C4的几种等位基因形式的氨基酸序列似乎非常相似，C4A和C4B的等位基因之间只有不到1%的残基位置发生了变化。这些结果可能与HLA复合体特定单倍型相关的自身免疫性疾病易感性增加有关。
