RESEARCH FOR MOLECULAR EVOLUTION OF PROTEIN KINASE C GENES OF PROTISTA EUGLENA GRACILIS Z AND ROLES OF THE KINASES.

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Protein kinases play important roles in the process of cell signaling. The kinases have been classified into 5 groups on the claster analysis inferred from their amino acid sequences. The protein kinase A (PKA), protein kinase G (PKG) and protein kinase C (PKC) are clastered each other in a group, AGC-family. It is well-known especially on vertebrate that each AGC-family protein kinse shows various function in signaling processes.The origin of the AGC-family kinase seems to be to single cell eucalyote such as protists. However, we have been much less informed about the molecular evolution of the kinases. Focussing these problems, new AGC-family protein kinases of a protist Euglena gracilus were screened. The single cell eucalyotic organism is a possible ancestor of all the multicelluler organisms, such as animal, plant and fungi. The protein kinase gene from Euglena gracilus were amplified by RT-PCR using several designed primers according to the consensus sequences along the kinase do … More main of the various AGC-kinase. Twelve fragments of protein kinase genes homologous to the PKA,PKC,S6-kinase and RACK genes were identified. A gene fragment showing widely similarity to AGC-kinase genes was used as a prove for selecting overall coding region of the kinase from the prepared cDNA libraries of Euglena gracilus z. Four clones having different kinase genes, but with high simirality each other, were obtained. The kinase genes (EPK-3, EPK-4, EPK-16, EPK-19) were sequenced. Northern analysis showed the single band corresponding 1.6Kb position. These new kinases havinf the several consensus sequences og typical AGC-kinases consist of a kinase domain without regulatory regions. Phyrogenetic analysis inferred from the amino acid sequences indicates that EPK family kinases make an claster out of PKA,PKC and other related kinases clasters. These results suppot the idea that the new type of protein kinase (EPK-family) is a possible origin of the well-known AGC-family kinases from various highly evolved organisms. Less