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 tripler structures ("structurizing regions" of chromosomal domains of the genes) were found in introns and at the flanks of three animal and two plant genes. If DNA-DNA interactions are the same in vivo, the chromosomal loci of eukaryotic genes could be compacted in several small loops. These interactions within a small region should result in formation of rosette-like structures. Clustering of the "structurizing regions" in chromosomal loci of the genes may be of functional importance.