Isolation and comparison of rat cDNAs encoding Ca2+/calmodulin-dependent protein kinase I isoforms.

For possible multiple isoforms of Ca2+/calmodulin-dependent protein kinase I (CaM kinase I), only one cDNA (CaM kinase I alpha) hitherto has to been cloned. By screening of embryonic (E18) rat brain cDNA libraries, we have now isolated two additional examples (CaM kinase I beta and gamma). Northern blot analysis revealed CaM kinase I alpha to predominate over I beta and gamma in rat brain. Analysis of the tissue distribution of the isoforms by reverse transcription-polymerase chain reaction (RT-PCR) protocols demonstrated CaM kinase I alpha in a variety of tissues while the expression of CaM kinase I beta and gamma was more limited to the brain. The obtained results support the idea that CaM kinase I exists as a set of isoforms.