Open AccessPresence of Non‐histone Proteins in Nucleosomes
Author(s) -
DEFER Nicole,
KITZIS Alain,
LEVY Florence,
TICHONICKY Lydie,
SABATIER MarieMadeleine,
KRUH Jacques
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb12484.x
Subject(s) - nucleosome , phosvitin , histone , histone h1 , chromatin , biochemistry , histone octamer , histone methylation , biology , chemistry , microbiology and biotechnology , biophysics , protein kinase a , kinase , dna , gene expression , gene , dna methylation
It has been established that nucleosomes are made of histones and DNA fragments. The purpose of this work was to establish whether some non‐histone proteins are also present in these chromatin subunits. We have found that nucleosome preparations contain phosphorylated non‐histone proteins and protein kinases by sucrose gradient analysis. In order to establish whether these proteins are actually bound to nucleosomes or if they represent unbound or aggregated proteins, the following experiments were performed. (a) Free non‐histone proteins and proteins released from chromatin by DNase overdigestion were analyzed by sucrose gradient centrifugation. No phosphoproteins but some phosvitin kinase activity was found in the part of the gradient which contained the nucleosomes. It could be assumed that part of the phosphoproteins are bound to nucleosomes. (b) A digestion of nucleosomes with DNase I suppressed the phosvitin kinase activity in the 11‐S region of the gradient. (c) High ionic strength, which extracted non‐histone proteins, suppressed the phosvitin kinase activity in the nucleosome region. Part of phosvitin kinase and of nuclear phosphoproteins are therefore bound to nucleosomes and are released by nuclease digestion and by high ionic strength.