Antibodies to the most tightly bound proteins in eukaryotic DNA. Formation of immuno-complexes with 'nuclear matrix' components.

Chromosomal DNA is associated with polypeptides covalently bound to internal DNA ends. Since these polypeptides can only be released from chromosomal DNA by enzymes or other agents hydrolysing phosphodiester bonds they were termed 'the most tightly bound' (MTB) polypeptides in DNA. Antibodies developed against the MTB polypeptides are shown to form immunocomplexes with major 'nuclear matrix' polypeptides as well as with polypeptides which are still associated with 'nuclear matrix' DNA isolated by means of SDS/proteinase K and phenol.

DNA polymerases in isolated 'nuclear matrix' of Ehrlich ascites cells.

Isolated nuclei from Ehrlich ascites tumor cells continue a replicative-like in vitro DNA synthesis. Polymerase alpha is the major dNTP polymerizing enzyme in nuclei. Following complete achromatinization dNTP polymerizing activities are still associated with the residual structure termed 'nuclear matrix'.