Devilee P, Slagboom P, Cornelisse C J, Pearson P L
Nucleic Acids Res. 1986 Mar 11;14(5):2059-73. doi: 10.1093/nar/14.5.2059.
We have cloned and determined the base-sequence and genome organization of two human chromosome-specific alphoid DNA fragments, designated L1.26, mapping principally to chromosomes 13 and 21, and L1.84, mapping to chromosome 18. Their copy number is estimated to be approximately 2,000 per haploid genome. L1.84 has a double-dimer organization, whereas L1.26 has a much less defined higher order tandem organization. Further, we present evidence that the restriction-site spacing within the alphoid DNA family is chromosome specific. From sequence analysis, clones L1.26 and L1.84 are found to consist of 5 and 4 tandemly duplicated 170 bp monomers. Cross-homology between the various monomers is 65-85%. The analysis suggests that the evolution of tandem-arrays does not take place via a defined 340 bp unit, as was inferred by others, but via circularly permutated monomers or multimers of the 170 bp unit.
我们已经克隆并确定了两个人类染色体特异性α卫星DNA片段的碱基序列和基因组组织，分别命名为L1.26，主要定位于13号和21号染色体，以及L1.84，定位于18号染色体。它们的拷贝数估计为每个单倍体基因组约2000个。L1.84具有双二聚体结构，而L1.26具有定义不太明确的高阶串联结构。此外，我们提供证据表明α卫星DNA家族内的限制性酶切位点间距是染色体特异性的。通过序列分析，发现克隆L1.26和L1.84分别由5个和4个串联重复的170 bp单体组成。各种单体之间的交叉同源性为65-85%。分析表明，串联阵列的进化不是通过其他人推断的定义明确的340 bp单元进行的，而是通过170 bp单元的环状排列单体或多聚体进行的。
