Lamin B content in chromatin fractions after purification of nuclear matrix from cells of different types.

We analyzed the content of lamin B, one of the main proteins of the nuclear membrane, in different chromatin fractions obtained during purification of the nuclear matrix from different cell types. Depending on cell type and nuclear matrix preparation technique, lamin B was found in different not associated with matrix chromatin compartments. This effect was observed after chromatin extraction with ammonium chloride after nucleolysis and after chromatin extraction with sodium chloride before nuclease treatment. These findings suggest that the structure of the nuclear matrix is destabilized in certain extraction procedures and that studies of subcompartmentalization of nuclear macromolecules require additional control of nuclear matrix integrity.