Production of antibody to phosphoprotein associated with nucleosome structure

Antibodies were produced to phosphoprotein fraction, and a phosphoprotein B2 obtained by carboxyl methyl cellulose column chromatography and sodium dodecyl sulfate (SDS) - polyacrylamide gel electrophoresis as described previously (Biochem. J. 183, 147 (1979)). Production of the specific antibody was confirmed by double immunodiffusion. The phosphoprotein B2 (relative mass 68 000), which was isolated from the phosphoprotein fraction by SDS-polyacrylamide gel electrophoresis, specifically reacted with the antisera, as identified by "rocket" immunoelectrophoresis. Further characterization of the antibody to the phosphoprotein was carried out by isoelectrofocusing gel electrophoresis. The phosphoprotein, previously identified in the isoelectric point (pI) region 6.2--8.5, was subsequently reacted with antisera and 125I-labelled protein A. A prominent radioactive peak was identified in the region in which the phosphoprotein was focused. The radioimmunoactivity was proportional to the amount of phosphoproteins present in the isoelectric focusing gel. The presence of phosphoprotein antibody. The relationship between the phosphoprotein and chromatin structure, and possible role in gene regulation is discussed.