Protein kinase Cβ and δ selectively phosphorylate odorant and metabotropic glutamate receptors

Recombinant protein segments from a metabotropic glutamate receptor and from an odorant receptor were used as substrates in protein kinase C phosphorylation assays. Protein kinase Cβ and δ phosphorylated an intracellular consensus phosphorylation site in the metabotropic glutamate receptor. Only protein kiase Cδ phosphorylated a novel extracellular consensus phosphorylation site in the odorant receptor. These results suggest differential regulation of these receptors by protein kinase C isotypes.