A cDNA, cRKIN1, encoding a putative homologue of the yeast (Saccharomyces cerevisuiae) SNFl (6), human cells (7), and Xenopus (8) are also present in pea (9) and Arabidopsis (10). All protein kinases that have been characterized in detail contain a number of key residues and conserved regions in the catalytic domain (11) but can be divided into two classes: those that phosphorylate serine/threonine residues and those that phosphorylate tyrosine residues. In the present report, we present the nucleotide sequence of a cDNA, cRKIN1,** isolated from a rye endosperm cDNA library. The cRKIN1-encoded protein contains all the invariant residues and conserved domains characteristic ofeukaryotic protein-serine/threonine kinases. It is particularly similar to the product ofthe SNFJ gene of yeast (Saccharomyces cerevisiae) (12), a protein affecting global regulation of carbon metabolism, and the expression of cRKIN1 in yeast snfl mutants restores SNFJ function.