大鼠肝脏染色质组分中核蛋白与转录活性序列的分布

The distribution of nuclear proteins and transcriptionally-active sequences in rat liver chromatin fractions.

作者信息

Mironov N M, Lobanenkov V V, Goodwin G H

出版信息

Exp Cell Res. 1986 Dec;167(2):391-9. doi: 10.1016/0014-4827(86)90179-5.

Abstract

Chromatin fractions from rat liver nuclei digested by nucleases were separated by differential solubility into several fractions. Material solubilized during digestion (predominantly monomer nucleosomes and polynucleosomes) had the highest HMG14 + 17/DNA ratios but were not enriched in active gene sequences (albumin and c-Ha-ras1 genes). Material soluble in a low ionic strength buffer containing 0.2 mM MgCl2 (monomer nucleosomes and polynucleosomes) contained in addition to the histones, HMG14 and 17 plus a 41K non-histone protein. This fraction was depleted in active gene sequences and enriched in inactive sequences. The insoluble material was highly enriched in active sequences and had the lowest HMG14 + 17/DNA ratio. This fraction could be further fractionated into a histone-containing 2 M NaCl-soluble fraction and a 2 M NaCl-insoluble matrix-bound fraction, both of which were enriched in active sequences. The results show that the HMG proteins do not partition with active sequences during fractionation of chromatin. The 41K protein may be associated with inactive chromatin fraction.

摘要

用核酸酶消化大鼠肝细胞核得到的染色质组分，通过不同溶解度被分离成几个组分。消化过程中溶解的物质（主要是单体核小体和多聚核小体）具有最高的HMG14 + 17/DNA比率，但在活性基因序列（白蛋白和c-Ha-ras1基因）中未得到富集。除组蛋白、HMG14和17外，可溶于含0.2 mM MgCl2的低离子强度缓冲液中的物质（单体核小体和多聚核小体）还含有一种41K非组蛋白。该组分在活性基因序列中减少，在非活性序列中富集。不溶性物质在活性序列中高度富集，且HMG14 + 17/DNA比率最低。该组分可进一步分离成含组蛋白的2 M NaCl可溶组分和2 M NaCl不溶的与基质结合的组分，两者在活性序列中均得到富集。结果表明，在染色质分级分离过程中，HMG蛋白不会与活性序列一起分配。41K蛋白可能与非活性染色质组分相关。