Nuclear Proteins of Neoplastic Cells

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Publisher Summary Proteins and enzymes of the nucleus are important for the synthetic reactions involved in neoplastic cells and to the aberrations of growth that characterize these cells. It has been difficult to isolate and purify the proteins of the nucleus but in recent years, the enzymatic activities of some of these proteins have been elucidated. In studies on the nuclear proteins, it is important that the nuclei be isolated in such a manner that the nuclear proteins remain in the nucleus, and the proteins of the cytoplasm do not enter the nucleus or contaminate the preparation. The high rate of biosynthesis of both histones and acidic nuclear proteins in the growing tissues and neoplastic cells are associated with rapid biosynthesis of DNA. However, even in resting cells, there is biosynthesis of all nuclear proteins. Because the possibility exists that the individual substructures of the nucleus of tumor cells contain proteins important both to their structural and functional characteristics, it is essential to consider the kinds of structures from which the nuclear proteins may originate and the methodology for their isolation. The criteria generally used to evaluate the purity of nuclei are that the nuclei should be anatomically identical with those of the whole cell, the contents of the nuclei as they exist in the cell should all be present in the isolated product, and the isolated nuclei should not contain cytoplasmic constituents. The chapter describes the techniques for isolation of nuclei and isolation of nuclear components. Further, the enzymes of the nucleus, the acidic nuclear proteins, nuclear globulins, the nuclear ribonucleoproteins, acidic proteins of the deoxyribonucleoprotein complex, and the histones have also been discussed in the chapter.