THE MSK FAMILY OF ALFALFA PROTEIN-KINASE GENES ENCODES HOMOLOGS OF SHAGGY GLYCOGEN-SYNTHASE KINASE-3 AND SHOWS DIFFERENTIAL EXPRESSION PATTERNS IN PLANT ORGANS AND DEVELOPMENT

This paper reports on the isolation of a novel class of plant serine/t hreonine protein kinase genes, MsK-1, MsK-2 and MsK-3. They belong to the superfamily of cdc2-like genes, but show highest identity to the D rosophila shaggy and rat GSK-3 proteins (65-70%). All of these kinases share a highly conserved catalytic protein kinase domain. Different a mino-terminal extensions distinguish the different proteins. The diffe rent plant kinases do not originate from differential processing of th e same gene as is found for shaggy, but are encoded by different membe rs of a gene family. Similarly to the shaggy kinases, the plant kinase s show different organ-specific and stage-specific developmental expre ssion patterns. Since the shaggy kinases play an important role in int ercellular communication in Drosophila development, the MsK kinases ar e expected to perform a similar function in plants.