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载脂蛋白 B(apo B)是引起动脉粥样硬化病的重要危险因子之一,研究apo B基因的结构、功能及其与疾病的关系是极其重要的.从已有的研究结果证明,apo B基因含29个外显子,5’末端3kb的区域内分别含有加强子(Enhancer)、启动子(Promoter)和衰减子(Reducer).不久前发现,apo B基因的3’末端第二个多聚A后面约500～800 bp的片段是一个高可变的重复序列(hyper-variable number of tandem repeats,VNTR),每15个核苷酸为一个重复单位,该序列中富含A和T,把(ATAATTAAATATTTT)命名为X,(ATAATTAAAATATTT)命名为Y,在该片段中若T,A被G,C取代,这样的重复序列被统称为X,Y的变异体,按其取代位置分别命名为Xi,Xii,Xiii,Yi,Yii和Yiii(图1)。
Apolipoprotein B (apo B) is one of the important risk factors of atherosclerosis.It is very important to study the structure and function of apo B gene and its relationship with the disease.Based on the results of previous studies, apo B The B gene contains 29 exons and the 5 ’end of the 3 kb region contains Enhancer, Promoter and Reducer, respectively. Not long ago, it was found that the apo B gene at the 3’ end of the second A fragment of about 500 to 800 bp behind the poly A is a hyper-variable number of tandem repeats (VNTRs), one repeat unit every 15 nucleotides, which is rich in A and T (ATAATTAAATATTTT) is named as X, (ATAATTAAAATATTT) is named as Y, and if T and A are replaced by G and C in this fragment, such repeats are collectively referred to as X and Y variants and are named according to their substitution positions Xi, Xii, Xiii, Yi, Yii and Yiii (Figure 1).