[Proteins bound to satellite DNA, are present in human nuclear matrix cell preparations]

The presence of protein or complex of proteins that specifically bind to human satellite 3 (HS3) was shown during investigations of the nuclear matrix. The specificity of binding of HS3 was shown by using nuclear matrix immobilized on nitrocellulose. The activity disappeared after extractions of the nuclear matrix. The presence of specific activity in low salt extract was shown by gel retardation assay with whole HS3 fragment. All the subfragments of HS3 after Sau3A restriction (1 kb, 0.36 kb, 0.41 kb) also retarded in the mixture with this protein extract. DNA-protein complexes were stable even in the presence of a 1000-fold excess of competitive DNA. These data are discussed in the frame of hypotheses about the three dimensional organization of interphase chromatin.