RECONSTITUTION OF HETEROLOGOUS AND CHIMERIC CASEIN KINASE-II WITH RECOMBINANT SUBUNITS FROM HUMAN AND DROSOPHILA - IDENTIFICATION OF SPECIES-SPECIFIC DIFFERENCES IN THE BETA-SUBUNIT

Casein kinase IT is composed of two catalytic (alpha) and two regulato ry (beta) subunits, the amino acid sequences of the alpha and beta sub units are highly conserved between species. To examine whether heterol ogous casein kinase II could be formed, recombinant alpha and beta sub units from human and Drosophila were reconstituted from inclusion bodi es. Casein kinase II containing either human alpha and Dposophila beta or Drosophila alpha and human beta subunits exhibited enzymatic prope rties similar to those of the homologous holoenzymes with regard to sp ecific activity, salt optima, and autophosphorylation. However, renatu ration and reconstitution of casein kinase II was dependent on the typ e of beta subunits and the redox conditions, with the Drosophila beta subunits requiring more reduced conditions. Chimeric beta subunits pre pared from human and Drosophila cDNA revealed that the N-terminal regi on was responsible for the requirement for the reduced redox state dur ing renaturation. The N-terminal region also affected solubility and e lectrophoretic mobility of the beta subunit.