人群变异的分子基础:从单核苷酸多态性到单氨基酸多态性

SNPs and SAPs are Molecular Bases of Population Variation

单核苷酸多态性可以划分为位于基因编码区的SNP和非编码区的SNP两大种类;而在基因编码区的SNP还可以进一步划分为两个亚类:不改变氨基酸序列的同义SNP和改变氨基酸序列的非同义SNP.显然,非同义SNP将导致氨基酸序列的改变,即形成单氨基酸多态性.基于蛋白质组学方法,对亚洲人群血浆样本中的SAP进行了系统研究,发现某一特定SAP在纯合人群和杂合人群中可能与生理或病理性状有着不同的关联.更为重要的是,近期有研究发现,在生物体中广泛存在着RNA序列与DNA序列不一致的现象.导致这种差异的主要原因是在转录水平上存在着规模化的RNA编辑(被称为RNA编辑组,RNA editome).该发现表明,个体拥有的SAP中可能有一部分与基因组SNP无关,而是源于RNA编辑组.进一步推论,可能在翻译水平上存在着不依赖DNA和RNA序列的全新的SAP.

There are two types of single nucleotide polymorphisms （SNPs）： within coding regions and within non-coding regions. SNPs within coding regions should be further divided into two categories： synonymous and non-synonymous. The non-synonymous SNPs can result in variation of amino-acid sequences, which are single amino-acid polymorphisms （SAPs）. Recently, using quantitative proteomic approaches, SAPs in the plasma proteomes were identified at population level for the first time, which showed that heterozygous and homozygous proteins with various SAPs have different associations with particular traits in the population. RNA editome that has been uncovered recently might be a new source of SAPs. In addition, there is another possible source of SAPs that is de hove one independent on both DNA and RNA sequences.