After removal, by high-salt extraction, of the loosely-bound components present in human placenta chromatin, tightly-bound cationic proteins could be solubilized, by acid extraction, from the 'stripped' chromatin, as well as from the 'stripped' loops or from the 'digested matrix'. These acid-soluble tightly-bound proteins are, in terms of apparent molecular mass and immunoreactivity, quite similar to the 'typical', loosely-bound histones, and, similarly to their 'loosely-bound' counterparts, they can be subdivided in distinct H-1-, H-2A-, H-2B-, H-3- and H-4-like components, the 'digested matrix' being however characterized by the absence of tightly-bound H-1. These tightly-bound histones, at variance from the 'typical' ones, readily find a right-handed helical conformation upon renaturation by progressive dialyses. The H-1 components strongly differ also in their effects on enzymic DNA methylation: while 'typical' H-1 has a strong inhibitory effect, its tightly-bound counterpart exerts a slight but definite stimulation.

Histones and DNA methylation in mammalian chromatin. II. Presence of non-inhibitory tightly-bound histones

ALLEGRA, Paola;
1991-01-01

Abstract

After removal, by high-salt extraction, of the loosely-bound components present in human placenta chromatin, tightly-bound cationic proteins could be solubilized, by acid extraction, from the 'stripped' chromatin, as well as from the 'stripped' loops or from the 'digested matrix'. These acid-soluble tightly-bound proteins are, in terms of apparent molecular mass and immunoreactivity, quite similar to the 'typical', loosely-bound histones, and, similarly to their 'loosely-bound' counterparts, they can be subdivided in distinct H-1-, H-2A-, H-2B-, H-3- and H-4-like components, the 'digested matrix' being however characterized by the absence of tightly-bound H-1. These tightly-bound histones, at variance from the 'typical' ones, readily find a right-handed helical conformation upon renaturation by progressive dialyses. The H-1 components strongly differ also in their effects on enzymic DNA methylation: while 'typical' H-1 has a strong inhibitory effect, its tightly-bound counterpart exerts a slight but definite stimulation.
1991
1129
43
48
Paola Caiafa;Anna Reale;Maria D'Erme;Paola Allegra;Raffaella Santoro;Roberto Strom
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/112037
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