Cloning and expression of genes coding for protein kinase CK2 alpha and beta subunits in zebrafish (Danio rerio)

cDNA clones coding for the alpha and beta subunits of protein kinase 2 (CK2) in zebrafish (Danio rerio) have been isolated. Sequencing of the cDNA clones has demonstrated that one contains the complete coding sequence for the beta subunit of CK2 while the alpha clone is truncated and lacks 183 nucleotides of the 5' coding region. Comparison of the deduced amino acid sequences shows an extremely high degree of evolutionary sequence conservation of these two proteins. Northern analysis of the mRNAs coding for the alpha subunit indicates that this messenger is present in 1 h embryos as a 3.6 Kb and a 1.9 Kb species, both of which decrease in 24-h embryos. In the case of beta, the major mRNA species of approximately 1.7 Kb maintains its level during the period of embryogenesis studied. In situ hybridization of early embryos, using antisense RNAs against alpha and beta mRNAs demonstrates temporal and tissue specific expression patterns. The alpha mRNA decreases after blastula, when it is evenly distributed. The beta mRNA is maintained at high levels between 4 and 24 h of development, showing in 18 h embryos a higher concentration in the developing neural tube and in the embryonic optic and otic vesicles.