Screening of isolated DNA for sequences released from anchorage sites in nuclear matrix.

Isolated chromosomal DNA is associated with polypeptides that are not released from DNA by several methods designed to purify DNA, e.g. treatment with sodium dodecyl sulphate.

Phosphodiester bonds between polypeptides and chromosomal DNA.

Polypeptides co-purifying with DNA in alkali are covalently bound to DNA. DNA purified by treatment with alkali, sodium dodecyl sulphate and phenol absorbed 125I under conditions designed to radioiodinate exclusively tyrosine and histidine in peptides. A significant amount of the absorbed 125I remained associated with DNA during treatment with phenol as well as during precipitation with ethanol from neutral and alkaline solutions.