Human alphoid family of tandemly repeated DNA. Sequence of cloned tetrameric fragments and analysis of familial divergence.
Human alphoid family of tandemly repeated DNA. Sequence of cloned tetrameric fragments and analysis of familial divergence.
复制标题
串联重复 DNA 的人类阿尔菲家族。
DOI：
10.1016/0022-2836(85)90254-2
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发表时间：
1985
影响因子：
5.6
通讯作者：
Goldstein,S
中科院分区：
文献类型：
--
作者：
ShmooklerReis,RJ;Srivastava,A;Beranek,DT;Goldstein,S
克隆了人着丝粒DNA（α DNA）170个碱基对单体重复单元的三个四聚体，并测定了它们的序列。相邻亚基的序列差异为30%至45%，而二聚体的差异为13%至20%，无论相邻与否。分歧是不均匀地分布在整个单体序列，这样两个高度保守的片段毗邻集群的插入/缺失。从克隆的序列计算或通过热不稳定的错配的重新关联的双链体在未克隆的DNA中测量的分歧，远远大于以前估计的总人类alphoid家族。然而，人类基因组中这些重复序列的数量并不是均匀分化的，因为α DNA的限制性子集仅包含总分化水平的十分之一。这表明基因组重复群体的等级或家族结构。使用克隆的探针，人α DNA被证明是高度甲基化和转录活性。这些数据，沿着的证据保守的片段和周期性（二聚体和高阶）覆盖相当大的序列多样性，支持这个DNA家族的结构作用。
Three tetramers of the 170 base-pair monomer repeat unit of human centromeric DNA (alphoid DNA) have been cloned and sequenced. Adjacent subunits differed in sequence by 30 to 45%, while dimers varied by 13 to 20% whether adjacent or not. Divergence was distributed unevenly across the monomeric sequence, such that two highly conserved segments adjoined clusters of insertions/deletions. Divergence, calculated from the cloned sequences or measured in uncloned DNA by thermal destabilization of mismatched reassociated duplexes, was far greater than previously estimated for the total human alphoid family. The population of these repeats within the human genome was not uniformly diverged, however, since restriction subsets of alphoid DNA contained as little as one-tenth the overall level of divergence. This indicates a hierarchical or familial structure of the genomic repeat population. Using cloned probes, human alphoid DNA was shown to be highly methylated and transcriptionally inactive. These data, along with evidence of conserved segments and periodicities (dimeric and higher-order) overlying considerable sequence diversity, support a structural role for this DNA family.