Specifically phosphorylates the agonist-occupied form of the beta-adrenergic and closely related receptors. [beta-adrenergic receptor] + ATP = [beta-adrenergic receptor]-phosphate + ADP + H(+) Interacts with GIT1. Expressed in brain cortex, hippocampus, striatum, hypothalamus, cerebellum and brainstem (at protein level). Ubiquitinated. Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family. GPRK subfamily.