G protein-coupled receptor kinase 4 (G protein-coupled receptor kinase GRK4, ITI1, GRK4, GPRK2L, GPRK4)

Function

• specifically phosphorylates activated forms of G protein-coupled receptors
• GRK4-alpha can phosphorylate rhodopsin & its activity is inhibited by calmodulin; the other three isoforms do not phosphorylate rhodopsin & do not interact with calmodulin

ATP + [G-protein-coupled receptor]
               <-->
ADP + [G-protein-coupled receptor]-phosphate

Structure

• belongs to the protein kinase superfamily, AGC Ser/Thr protein kinase family, GPRK subfamily
• contains 1 AGC-kinase C-terminal domain
• contains 1 protein kinase domain
• contains 1 RGS domain

Alternative splicing

named isoforms=4

Expression

• expressed in testis, & in a lower extent in other tissues including brain cortex & striatum

More general terms

• G protein-coupled receptor kinase

Database

• OMIM: https://mirror.omim.org/entry/137026
• UniProt: http://www.uniprot.org/uniprot/P32298.html