This is a family of PrkA bacterial and archaeal serine kinases approximately 630 residues long. This family corresponds to the C-terminal domain [1].

1: Cloning and characterization of the Bacillus subtilis prkA gene encoding a novel serine protein kinase. Fischer C, Geourjon C, Bourson C, Deutscher J; Gene 1996;168:55-60. PMID:8626065