The function of ENSG00000100077 (GRK3, G protein-coupled receptor kinase 3) is as follows. Specifically phosphorylates the activated forms of G protein- coupled receptors (PubMed:21799898). Such receptor phosphorylation initiates beta-arrestin-mediated receptor internalization, and signaling events leading to their desensitization (PubMed:21799898). Phosphorylates the agonist-occupied form of the beta-adrenergic and closely related receptors (By similarity). Also phosphorylates ligand- bound C3a and C5a anaphylatoxin receptors (C3AR1 and C5AR1, respectively), leading to receptor desensitization (PubMed:21799898). Positively regulates ciliary smoothened (SMO) signaling pathway by mediating phosphorylation of SMO, facilitating SMO trafficking into the cilium and the stimulation of SMO activity (By similarity). {ECO:0000250|UniProtKB:P26819, ECO:0000250|UniProtKB:Q3UYH7, ECO:0000269|PubMed:21799898}.