G protein-coupled receptor kinases (GRKs) play an important role in phosphorylating and regulating the activity of a variety of G protein-coupled receptors. Haribabu and Snyderman (1) identified GRK5 and GRK6. GRK5 is a member of the guanine nucleotide-binding protein (G protein)-coupled receptor kinase subfamily of the Ser/Thr protein kinase family. It phosphorylates the activated forms of G protein-coupled receptors thus initiating their deactivation. It has also been shown to play a role in regulating the motility of polymorphonuclear leukocytes (PMNs). Bullrich (2) used a rodent-human hybrid panel to map 2 newly identified members of the GRK family: GPRK5 and GPRK6 to 10q24-qter and 5q35, respectively. Desensitization of G protein-coupl