SPECIFIC DNA-PROTEIN INTERACTIONS DURING ROSETTE-LIKE STRUCTURE (ELEMENTARY CHROMOMERE) FORMATION AND DURING ASSOCIATION OF INTERPHASE CHROMOSOMES WITH NUCLEAR-ENVELOPE

The specificity of DNA-protein interactions was studied during formati on of two main types of nuclear DNA loops in the interphase chromosome s: loops with their bases anchored at the nuclear envelope, and loops with bases fixed by the core proteins of rosette-like structures. Both types of DNA-protein interaction were shown to be highly specific. Co ntrary to the nuclear envelopes, the cores of rosette-like structures selectively bind supercoiled rather then relaxed molecules of the pUC1 9 DNA. A protein of 95 kDa specifically binding double-stranded DNA fr agments from the rosette cores, and DNA topoisomerase II were identifi ed among the polypeptides of the rosette core.