Calmodulin binding to the cytoskeletal neuronal calmodulin-dependent protein kinase is regulated by autophosphorylation.
- 1 January 1985
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 82 (2), 287-291
- https://doi.org/10.1073/pnas.82.2.287
Abstract
A brain cytoskeletal preparation that is highly enriched in calmodulin-dependent protein kinase facilitated the study of the binding of 125I-labeled calmodulin to the native enzyme. The binding was specific, saturable, Ca2+-dependent, and inhibited by trifluoperazine. Stoichiometric analysis revealed that the ratio of bound calmodulin to the alpha subunit of the protein kinase was about 1:10 (+/-30%), indicating that in the native state not all of the enzyme subunits were accessible to bind calmodulin. The Kd for the binding reaction was 7 X 10(-9) M and was subject to regulation by divalent cations other than Ca2+, decreasing to 1.7 X 10(-9) M in the presence of 7 mM MgCl2. Activation of the protein kinase in the presence of Ca2+ and calmodulin resulted in marked autophosphorylation of the enzyme subunits. The autophosphorylation was accompanied by a 2-fold decrease in the affinity and number of 125I-labeled calmodulin binding sites. This effect was also reflected by an increase in the apparent Km for Ca2+ from 90 to 200 X 10(-9) M. Thus, enzyme autophosphorylation appears to represent a negative feedback signal, rendering the enzyme less sensitive to subsequent stimulation by physiologic increases in the intracellular Ca2+ concentration. These results help to clarify the mode of neuronal intracellular Ca2+ signaling.Keywords
This publication has 15 references indexed in Scilit:
- Ca2+/calmodulin-dependent protein kinases from the neuronal nuclear matrix and post-synaptic density are structurally related.Proceedings of the National Academy of Sciences, 1984
- Phosphorylation of microtubule-associated proteins by a Ca2+/calmodulin-dependent protein kinase.The Journal of cell biology, 1984
- Changes in free-calcium levels and pH in synaptosomes during transmitter releaseBiochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1984
- Identification of the Major Postsynaptic Density Protein as Homologous with the Major Calmodulin‐Binding Subunit of a Calmodulin‐Dependent Protein KinaseJournal of Neurochemistry, 1984
- Evidence that the major postsynaptic density protein is a component of a Ca2+/calmodulin-dependent protein kinase.Proceedings of the National Academy of Sciences, 1984
- Function of a calmodulin in postsynaptic densities. III. Calmodulin-binding proteins of the postsynaptic density.The Journal of cell biology, 1981
- A Rapid and Sensitive Method for the Quantitation of Microgram Quantities of Protein Utilizing the Principle of Protein-Dye BindingAnalytical Biochemistry, 1976
- Methodology for in vitro studies of Ca2+ transportAnalytical Biochemistry, 1975
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970