Acta Biochimica et Biophysica 9. (1974)
1974 / 1-2. szám - Takáts, A.-Faragó, A.-Antoni, F.-Fábián, F.: Adenosine 3':5' Monophosphate Dependent Protein Kinase Isolated from Rat Harderian Gland
Acta Biochim. et Biophys. Acad. Sei. Hung. Vol. 9 (1—2), pp. 33 — 41 (1974) Adenosine 3’ : 5’-Monophosphate Dependent Protein Kinase Isolated from Rat Harderian Gland A. Takáts, Anna Faragó, F. Antoni, F. Fábián Institute of Medical Chemistry, Semmelweis University of Medicine, Budapest, and Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary (Received August 29, 1973 and in revised form December 10, 1973) A relatively high, cyclic AMP-dependent histone kinase activity was found in rat Harderian gland. Some properties of this enzyme were studied after purification. The maximal activation of the enzyme was attained at 10-6M cAMP. At higher concentrations cAMP inhibited the reaction. Half-maximal activation was brought about by 1.1X10~8M cAMP, and also by 2.5 X 10-8 M N6-butyryl-cAMP or about 10-6 M cGMP. In the presence of cAMP the apparent Km values of the different histone fractions (fl, f2a, f2b and f3) were markedly decreased. The f2b fraction was preferentially phosphorylated by this enzyme. After tryptic digestion of the phosphorylated f2b histone a single [32P]-phosphopeptide fragment was detectable in the two dimensional paper electrophoretic map. Introduction The presence of cyclic AMP-dependent protein kinases has been demonstrated in several animal tissues (Krebsetal., 1964; Langan, 1968; Kuo et ah, 1970) and in some cases the exact role of these enzymes in regulation has also been clarified (Soderling, FLickenbottom, 1970). In eukaryotic cells most of the wide variety of effects elicited by cAMP may be mediated through stimulation of protein kinases (Kuo, Greengard, 1969). The cyclic AMP-activated phosphorylation of histones may also be a part of an important regulatory process (Langan, 1968), although the function of histone-phosphorylation is yet unclear. The common properties of cAMP-dependent histone kinases isolated from different tissues may give some information for the better understanding of their function. In the present work the cAMP-dependent histone kinase of rat Harderian gland has been investigated. Abbreviations used: cAMP, adenosine 3’:5'-monophosphate; cGMP, guanosine 3’: 5’-monophosphate; TCA, trichloroacetic acid. 3 Acta Biochimica et Biophysica Academiae Scientiarum Hungaricae 9, 1974