THE CDNA SEQUENCE AND CHARACTERIZATION OF THE CA2+ CALMODULIN-DEPENDENT PROTEIN KINASE-GR FROM HUMAN BRAIN AND THYMUS/

We have isolated and sequenced cDNAs encoding Ca2+/calmodulin-dependen t protein kinase type Gr (CaM-K-Gr, also called CaM-K-IV) from human b rain and thymus. The sequence of the protein coding region of the cDNA is identical in both brain and thymus, although Northern hybridizatio n analysis shows variation of the mRNA transcripts in these tissues. T he sequence predicts a protein of M(r) 51897 that is 83.7% identical a nd shows 89.2% similarity with the rat homologue. The deduced human Ca M-K-Gr is identical to the rat and mouse proteins in the portion of th e enzyme involved in ATP binding, the catalytic domain and Ca2+/calmod ulin-binding domain; however, the N terminus of the human kinase, whic h may comprise a second regulatory domain [McDonald et al., J. Biol. C hem. 268 (1993) 10054-10059], contains a 4-amino-acid (aa) insertion r elative to the rodent enzymes. Additionally, the C-terminal associatio n domain shows only 45.2 and 41.6% identity with the rat and mouse pro teins, respectively, suggesting that this domain is not constrained by stringent structural and functional requirements. Based on the predic ted aa sequence of the human kinase, we produced polyclonal antisera a gainst a C-terminal peptide that recognizes two forms of CaM-K-Gr in h uman T-cell lymphoma and neuroblastoma cell lines. The human antiserum cross-reacts with the rat and mouse proteins and immunoprecipitates t he active kinase.