Binding of RP2-L—a Nuclear Protein of Neoplastic Tissues—to Deoxyribonucleic Acid

Abstract

RECENT work in this laboratory has indicated that the incorporation of radioactive amino-acids into nuclear proteins, especially the acid-soluble nuclear proteins, represents an important metabolic pathway in transplantable rat tumours^1–3. The acid-soluble nuclear proteins obtained from rats injected with L-lysine-U-¹⁴C were chromatographed on carboxymethyl-cellulose columns⁴ after the acid extracts had been dialysed against 0.5 N acetic acid. The cellulose columns (sodium form) had been equilibrated against 0.05 M sodium acetate buffer, pH 4.0. Gradient elution was used with N formic acid followed by 8 N formic acid. All procedures were carried out at 4° C. The resolving power of this method provided specific chromatographic patterns for protein distribution and distribution of radioactivity for the acid-soluble nuclear proteins of the Walker tumour and various tissues of the tumour-bearing rat. The chromatograms of the acid-soluble nuclear proteins from the various non-tumour tissues contained one to three radioactive peaks with relatively low specific activities. The chromatograms of the nuclear extracts of the Walker tumour, and a number of other malignant tumours, contained a radioactive peak which was not found in any of the growing or non-growing^4,5 non-tumour tissues studied.