INTERACTION OF CALMODULIN WITH MYOSIN LIGHT CHAIN KINASE AND CAMP-DEPENDENT PROTEIN-KINASE IN BOVINE BRAIN

  • 1 January 1981
    • journal article
    • research article
    • Vol. 256  (15) , 8183-8189
Abstract
Myosin light chain kinase and a fraction of type II cAMP-dependent protein kinase were partially purified from bovine brain by affinity chromatography on calmodulin-Sepharose. The myosin kinase was purified .apprx. 3700-fold and has an estimated MW of 130,000 .+-. 10,000 by sodium dodecyl sulfate gel electrophoresis. A fraction of soluble cAMP-dependent protein kinase also bound to calmodulin-Sepharose and was purified 2300-fold. A fraction of this cAMP-dependent protein kinase after purification by glycerol gradient centrifugation was shown to contain the 2 subunits of calcineurin, a major calmodulin-binding protein in brain, and the 2 subunits of type II cAMP-dependent protein kinase in a ratio of 1:1:2:2. Its sedimentation coefficient was 8.1 S and 9.0 S when centrifuged in the absence or presence of calmodulin, suggesting the formation of a complex between calmodulin and protein kinase. Calcineurin may be involved in the interaction between the protein kinase and calmodulin. Apparently, the regulatory subunit of the cAMP-dependent protein kinase, but not the catalytic subunit, is the site of interaction with calmodulin since the catalytic subunit of protein kinase was partially resolved from the complex by cAMP.