Human tonsillar lymphocytes were fractionated by a hypotonic extraction procedure, followed by the purification and extraction of nuclei. Two different histone kinases could be separated by DEAE-cellulose chromatography from the hypotonic extract, each of which phosphorylated the F2b histone fraction preferentially. In the nuclear extract, a third histone kinase fraction was found, which primarily phosphorylated the F2a histone. Only one of the histone kinases, found in the hypotonic extract, was cyclic AMP dependent, and the other two enzymes were independent of the cyclic nucleotide. In contrast with the other two histone kinases the cyclic AMP-dependent enzyme had a specific effect, phosphorylating mainly one particular site of the F2b histone fraction in the presence of cyclic AMP.
ASJC Scopus subject areas
- Molecular Biology