Identification and partial purification of a chromatin bound calmodulin activated histone 3 kinase from calf thymus |
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Authors: | B T Wakim M M Picken R J DeLange |
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Institution: | Macromolecular Laboratory, Stritch School of Medicine, Loyola University of Chicago, Maywood, Illinois 60153. |
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Abstract: | A calcium-calmodulin (Ca2(+)-CaM) stimulated histone H3 phosphorylating activity was identified as a component of a nuclear protein complex purified from a 150 mM NaCl extract of calf thymus chromatin. This activity bound to a CaM-Sepharose affinity column in a Ca2+ dependent manner and was eluted off the column in the presence of EGTA. Equilibrium centrifugation of the EGTA eluate on a sucrose density gradient revealed that the activity is a component of a larger complex identified at 25% sucrose. This complex consisted of two major proteins, having Mr of 65 and 75 kDa. Using 125I] CaM and the gel overlay technique it was shown that the 75 kDa protein is the major CaM binding protein in the complex. |
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