Huang L S, Breslow J L
J Biol Chem. 1987 Jul 5;262(19):8952-5.
A DNA restriction fragment length polymorphism has been found immediately 3' to the human apoB gene. Digestion of many different human DNAs at sites flanking the region and Southern blotting analysis reveal that this region can vary in length by approximately 300 base pairs with five alleles readily distinguishable. The length polymorphism is due to a unique AT-rich minisatellite that consists primarily of a 30-base pair tandem repeat with two structurally related subunit sequences, x (ATAATTAAATATTTT) and y (ATAATTAAAATATTT). In general, the sequences repeat in an x-y order. The AT-rich region also contains variant x and y sequences that result from C or G for A substitution. Sequence analysis of one large allele revealed the expected increased number of xy repeats. In addition, similar analysis of three different smaller alleles with the same apparent size on Southern blotting analysis showed that all were of slightly different size due to minor differences in the number of xy repeats. The heterogeneity of this AT-rich minisatellite provides the basis for a highly informative restriction fragment length polymorphism of the apoB gene and should be very useful in association and linkage analysis studies of the contribution of this locus to atherosclerosis susceptibility.
在人类载脂蛋白B基因3'端紧邻处发现了一种DNA限制性片段长度多态性。对该区域侧翼位点的许多不同人类DNA进行酶切并进行Southern印迹分析，结果显示该区域长度可相差约300个碱基对，有五个等位基因易于区分。这种长度多态性是由一个独特的富含AT的小卫星造成的，该小卫星主要由一个30个碱基对的串联重复序列组成，有两个结构相关的亚基序列，x（ATAATTAAATATTTT）和y（ATAATTAAAATATTT）。一般来说，这些序列按x-y顺序重复。富含AT的区域还包含由A被C或G替代产生的变异x和y序列。对一个大等位基因的序列分析显示xy重复序列数量预期增加。此外，对Southern印迹分析中大小相同的三个不同较小等位基因进行类似分析表明，由于xy重复序列数量的微小差异，它们的大小都略有不同。这种富含AT的小卫星的异质性为载脂蛋白B基因高度信息丰富的限制性片段长度多态性提供了基础，在该基因座对动脉粥样硬化易感性的贡献的关联和连锁分析研究中应该非常有用。
