High molecular mass phosphoproteins in the rat liver nuclear matrix identification of a prominent 110,000 Dalton species.

Purified rat liver nuclei were labelled in vitro in the presence of (32P) ATP and submitted to sequential extraction with DNAse, 0.4 or 2.0 M NaCl and Triton X-100. The residual or matrix structures contained 8-10 phosphoproteins between 76 and 260 kd including a triplet of major bands with 110, 117 and 128 kd. The 110 kd species was purified by chromatography on oligo(dT)-cellulose. It was shown to be identical with the 110 kd phosphoprotein of rat liver or Morris hepatoma free polyribosomes using the technique of limited digestion with S. aureus protease V 8.