Loc P V, Strätling W H
Institut für Physiologische Chemie, Universitäts-Krankenhaus Eppendorf, Universität Hamburg, FRG.
EMBO J. 1988 Mar;7(3):655-64. doi: 10.1002/j.1460-2075.1988.tb02860.x.
The matrix attachment regions of the chicken lysozyme domain were studied in an in vitro DNA binding assay by incubating oviduct nuclear matrices with labeled restriction fragments. A strong attachment region was localized between 11.1 and 8.85 kb upstream of the transcription start site and a weaker one between 1.3 and 5.0 kb downstream of the poly(A)+ addition site. Both attachment regions co-map with the previously established boundaries of the chromatin domain. The upstream matrix attachment region is distinguishable from known enhancers and is composed of multiple binding sites. We find specific but weaker binding of the same restriction fragments to matrix preparations from transcriptionally inactive chicken erythrocytes indicating a cell-type and transcription-independent conservation of the sites for specific binding of matrix attachment sequences. We also demonstrate that the matrix attachment regions are located at the base of a chromosomal loop in histone-extracted nuclei. Thus, the lysozyme domain represents a topologically-sequestered functional unit containing the coding region and all known lysozyme-specific, cis-acting regulatory elements.
通过将输卵管核基质与标记的限制性片段一起孵育，在体外DNA结合试验中研究了鸡溶菌酶结构域的基质附着区域。一个强附着区域定位在转录起始位点上游11.1至8.85 kb之间，一个较弱的附着区域定位在聚腺苷酸（poly(A)+）添加位点下游1.3至5.0 kb之间。两个附着区域都与先前确定的染色质结构域边界共定位。上游基质附着区域与已知的增强子不同，由多个结合位点组成。我们发现相同的限制性片段与转录不活跃的鸡红细胞的基质制剂有特异性但较弱的结合，这表明基质附着序列特异性结合位点在细胞类型和转录方面具有独立性。我们还证明，基质附着区域位于组蛋白提取核中染色体环的基部。因此，溶菌酶结构域代表一个拓扑隔离的功能单元，包含编码区和所有已知的溶菌酶特异性顺式作用调节元件。
