Components of a calmodulin-dependent protein kinase cascade. Molecular cloning, functional characterization and cellular localization of Ca2+/calmodulin-dependent protein kinase kinase beta.

Published

Journal Article

Ca2+/calmodulin-dependent protein kinases I and IV (CaMKI and CaMKIV, respectively) require phosphorylation on an equivalent single Thr in the activation loop of subdomain VIII for maximal activity. Two distinct CaMKI/IV kinases, CaMKKalpha and CaMKKbeta, were purified from rat brain and partially sequenced (Edelman, A. M., Mitchelhill, K., Selbert, M. A., Anderson, K. A., Hook, S. S., Stapleton, D., Goldstein, E. G., Means, A. R., and Kemp, B. E. (1996) J. Biol. Chem. 271, 10806-10810). We report here the cloning and sequencing of cDNAs for human and rat CaMKKbeta, tissue and regional brain localization of CaMKKbeta protein, and mRNA and functional characterization of recombinant CaMKKbeta in vitro and in Jurkat T cells. The sequences of human and rat CaMKKbeta demonstrate 65% identity and 80% similarity with CaMKKalpha and 30-40% identity with CaMKI and CaMKIV themselves. CaMKKbeta is broadly distributed among rat tissues with highest levels in CaMKIV-expressing tissues such as brain, thymus, spleen, and testis. In brain, CaMKKbeta tracks more closely with CaMKIV than does CaMKKalpha. Bacterially expressed CaMKKbeta undergoes intramolecular autophosphorylation, is regulated by Ca2+/CaM, and phosphorylates CaMKI and CaMKIV on Thr177 and Thr200, respectively. CaMKKbeta activates both CaMKI and CaMKIV when coexpressed in Jurkat T cells as judged by phosphorylated cAMP response element-binding protein-dependent reporter gene expression. CaMKKbeta activity is enhanced by elevation of intracellular Ca2+, although substantial activity is observed at the resting Ca2+ concentration. The strict Ca2+ requirement of CaMKIV-dependent phosphorylation of cAMP response element-binding protein, is therefore controlled at the level of CaMKIV rather than CaMKK.

Full Text

Duke Authors

Cited Authors

  • Anderson, KA; Means, RL; Huang, QH; Kemp, BE; Goldstein, EG; Selbert, MA; Edelman, AM; Fremeau, RT; Means, AR

Published Date

  • November 27, 1998

Published In

Volume / Issue

  • 273 / 48

Start / End Page

  • 31880 - 31889

PubMed ID

  • 9822657

Pubmed Central ID

  • 9822657

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.273.48.31880

Language

  • eng

Conference Location

  • United States