Phosphorylation of CREB by CaM-kinase IV activated by CaM-kinase IV kinase.
Previous reports have shown that CaM-kinase IV can phosphorylate the transcription factor CREB in vitro on Ser133. Furthermore, transfected CaM-kinase IV can activate CREB-dependent transcription, but at a lower efficiency than the cAMP-kinase. In this paper we examine the kinetics and site-specificity of CREB phosphorylation in vitro by CaM-kinase IV after its phosphorylation and activation by a newly discovered brain CaM-kinase IV kinase. Our results show that activated CaM-kinase IV has the same Km (1-5 microM) for CREB phosphorylation, but the Vmax is about 30-fold higher than with non-activated CaM-kinase IV. Activated CaM-kinase IV still shows specificity for phosphorylation of Ser133, the site necessary for transactivation by CREB. It is likely that the lower efficiency of transcriptional activation by transfected CaM-kinase IV in previous studies was due to the fact that the CaM-kinase IV was not activated by CaM-kinase IV kinase.
Enslen
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Vollum Institute, Oregon Health Sciences University, Portland 97201.
Tokumitsu
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Soderling
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D000595:Amino Acid Sequence; D001665:Binding Sites; D002118:Calcium / Q000494:pharmacology; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002147:Calmodulin / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D004789:Enzyme Activation; D007700:Kinetics; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011994:Recombinant Proteins; D013379:Substrate Specificity
D002147:Calmodulin; D017362:Cyclic AMP Response Element-Binding Protein; D011994:Recombinant Proteins; D010768:Phosphoserine; D017346:Protein Serine-Threonine Kinases; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium