title: [Distribution and enzymic hypermethylation of inverted DNA repeats in different murine and human cells (author's transl)].
abstract: A specific class of DNA sequences, the inverted repetitive sequences, forms a double-stranded structure within a single linear polynucleotide chain in denatured DNA. The reassociation process is unimolecular and occurs very fast. Quantitative analyses have shown that these sequences comprise about 4--5% of the nuclear DNA of various mammalian cells (P815 mouse mastocytoma, Hela, L cells, Raji and Chang cells, and human embryonic hepatocytes) and are interspersed within sequences of other degrees of repetitiveness. After labeling the cells with L-[Methyl-3H]methionine and [14C]deoxycytidine, relative rates of enzymic DNA methylation were computed on the basis of 3H and 14C radioactivities found in pyrimidine residues of the nuclear DNA. The results indicate that DNA of inverted repetitive sequences is methylated to a level about 50% higher than the ordinary repetitive sequences and to about 300% higher than the unique and intermediary sequences. The biological function of the inverted repeats as well as the role of their enzymic hypermethylation is unknown.
mesh_terms: D000818:Animals; D002460:Cell Line; D004247:DNA / Q000302:isolation & purification; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000302:isolation & purification; D006367:HeLa Cells / Q000032:analysis; D006801:Humans; D007739:L Cells / Q000032:analysis; D008780:Methyltransferases / Q000378:metabolism*; D051379:Mice; D010954:Plasmacytoma; D013045:Species Specificity
chemical_list: D004273:DNA, Neoplasm; D004247:DNA; D008780:Methyltransferases; D004248:DNA (Cytosine-5-)-Methyltransferases
vernacular_title: Verteilung und enzymatische Hypermethylierung invers repetitiver DNA-Sequenzen in verschiedenen Mäuse- und menschlichen Zellen.