A specific mouse satellite-binding protein of nuclear matrix

A 120-kDa protein (p120) specifically binding the major mouse satellite was detected by the gel retardation assay in liver nuclear matrix extract. The major satellite does not have a discrete binding site for p120; rather, mu ltiple contact regions are distributed along the whole satellite. The bindi ng is likely to depend on the structural properties of the major satellite, rather than on its specific nucleotide sequence. A number of p120 characte ristics resemble those of the MAR/SAR-binding protein SAF-A. Antibodies aga inst the major satellite-protein complexes reveal p120 in the mouse and hum an nuclear matrix. Immunofluorescence staining shows that p120 is mainly lo calized in the heterochromatin region and is probably involved in the forma tion of its structure.