Searching the genome sequence ofStreptococcus pneumoniaerevealed the presence of a single Ser⁄Thr protein kinase genestkP linked to protein phosphatasephpP. Biochemical studies performed with recombinant StkP suggest that this protein is a functional eukaryotic-type Ser⁄Thr protein vitrokinase assays and Western blots ofS. pneumoniaesubcellu-lar fractions revealed that StkP is a membrane protein.