CLONING AND CHARACTERIZATION OF A PLANT GENE ENCODING A PROTEIN-KINASE

The cloning and sequence analysis of a gene that encodes a homologue of protein kinase (PK) from Arabidopsis thaliana is reported. We screened a genomic DNA library of A. thaliana using as probes oligodeoxyribonucleotides or fragments from the polymerase chain reaction that correspond to conserved regions in the catalytic domains of various PKs. One genomic clone, named Atpk5, was sequenced and analyzed. Transcripts of the corresponding gene, Atpk5, were detected in root, leaf and flower tissues by Northern blot analysis. The deduced amino acid sequence of the putative product of Atpk5 resembles those of kinases that phosphorylate ribosomal protein S6, cAMP-dependent PKs and protein kinase C. From the results of sequence comparisons, the ATPK5 protein appears to be a member of a subfamily of Ser/Thr-PKs specific to plants.