THE ARABIDOPSIS SHAGGY-RELATED PROTEIN-KINASE (ASK) GENE FAMILY - STRUCTURE, ORGANIZATION AND EVOLUTION

Higher plants contain a multigene family encoding proteins that share a highly conserved catalytic protein kinase domain about 70% identical to SHAGGY protein kinase (SGG) and glycogen synthase kinase-3 (GSK-3) , respectively, from Drosophila and mammals. In this study we have cha racterized the structure and evolution of the Arabidopsis SHAGGY-relat ed protein kinase (ASK) gene family. At least ten ASK genes are presen t per haploid genome of Arabidopsis. The genomic sequences of live ASK genes show a strikingly high conservation of intron positions and exo n lengths. Phylogenetic analyses suggested that the Arabidopsis gene f amily contains at least three ancient classes of genes that diverged e arly in land plant evolution. The different classes may reflect specif icity of substrates and/or biological functions. Eight out oi the ten predicted ASK genes were mapped and shown to be dispersed over the fiv e Arabidopsis chromosomes. A tentative model for the organization and evolution of the Arabidopsis ASK genes is presented. (C) 1998 Elsevier Science B.V. All rights reserved.