Compactization of chromosomal loci in eukaryotic genes: Tripler DNA structures (a model)

Involvement of polypurine and polypyrimidine nucleotide sequences of DNA in compactization of gene chromosomal domains was analyzed. Tracts (10 bp or longer) of purines and pyrimidines potentially able to interact forming tri pler structures ("structurizing regions" of chromosomal domains of the gene s) were found in introns and at the flanks of three animal and two plant ge nes. If DNA-DNA interactions are the same in vivo, the chromosomal loci of eukaryotic genes could be compacted in several small loops. These interacti ons within a small region should result in formation of rosette-like struct ures. Clustering of the "structurizing regions" in chromosomal loci of the genes may be of functional importance.