title: Localization, in human placenta, of the tightly bound form of DNA methylase in the higher order of chromatin organization.
abstract: In human placenta, the DNA of all subfractions of the third level of chromatin organization exhibits similar values of the methylcytosine-to-cytosine ratio. The tightly bound form of DNA methyltransferase is mostly recovered in the 'stripped loop' fraction, although, on the basis of the DNA content, the 'stripped loops' and the 'stripped matrix' appear to possess a similar amount of the enzyme. DNA methyltransferase activity is instead totally absent from the 'digested matrix', i.e., from the fraction remaining after digestion of the 'stripped matrix' with DNAase I. Upon addition of exogenous DNA methyltransferase, however, the DNA of this fraction, which is only 1% (in weight) of the total chromatin DNA and which has a length of approx. 9 kbp, can readily undergo methylation.
authors.affiliation: Dipartimenti di Scienze Biochimiche, Università di Roma La Sapienza, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Caiafa
authors.forename: S
authors.initials: S
authors.lastname: Mastrantonio
authors.forename: F
authors.initials: F
authors.lastname: Cacace
authors.forename: M
authors.initials: M
authors.lastname: Attinà
authors.forename: M
authors.initials: M
authors.lastname: Rispoli
authors.forename: R
authors.initials: R
authors.lastname: Strom
mesh_terms: D044503:5-Methylcytosine; D002843:Chromatin / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D003596:Cytosine / Q000031:analogs & derivatives / Q000032:analysis; D004247:DNA / Q000032:analysis / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000032:analysis* / Q000378:metabolism; D003850:Deoxyribonuclease I; D004586:Electrophoresis; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D011506:Proteins / Q000032:analysis
chemical_list: D002843:Chromatin; D011506:Proteins; D044503:5-Methylcytosine; D003596:Cytosine; D004247:DNA; D004248:DNA (Cytosine-5-)-Methyltransferases; D003850:Deoxyribonuclease I