We will seek correlations between patterns of nuclear protein phosphorylation in normal human colon and colon carcinoma and the levels and substrate specificities of isolated protein kinases with the goal of locating neoplasia-related alterations in this regulatory system. We propose to isolate and purify histone and non-histone proteins of chromatin from normal human colon and colon carcinoma tissues and from 3T3 cells and their SV40-transformed counterparts. We plan also to isolate and purify the protein kinases from nuclei of these cells and to characterize them in terms of substrate specificity, cyclic nucleotide effects, and kinetic parameters. A preparation of soluble nuclear proteins from rat liver has been obtained which contains true histone phosphokinase activity. This enzyme preparation preferentially transfers phosphate from ATP to histone sub-groups f1, f3 and f2b. The enzyme, prepared from the livers of young (21-24 day old) rats, appears to differ significantly, notably in substrate preference, from previously described nuclear phosphokinases. In contrast to descriptions of nuclear kinases from mature rats, the activity measured in our nuclear sap protein preparations has a 10-fold greater specific activity than the chromatin-associated enzyme and contains 50-60 percent of the total nuclear phosphokinase activity. Endogenous protein is phosphorylated by the preparation only to the extent of 10-15 percent of activity observed in the presence of added histone. In contrast to other histone phosphokinases described, cAMP stimulates the activity only 2-fold. A Preliminary report has been published: Federation Proc. 34: 702 (1975).