PHOSPHORYLATION AND PALMITOYLATION OF THE HUMAN D2(L) DOPAMINE-RECEPTOR IN SF9 CELLS

We have expressed and biochemically characterized the human D2(long) ( D2(L)) dopamine receptor isoform using the baculovirus/Sf9 cell system . The expressed receptor bound ligands with a pharmacological profile similar to that reported for neuronal and cloned D2(L) receptors expre ssed in mammalian cell lines. Dopamine binding to D2(L) receptor was s ensitive to guanine nucleotides, indicating receptor coupling to endog enous G proteins. A D2(L) receptor-specific antibody identified two ma jor protein species at similar to 44 kDa and at similar to 93 kDa in i mmunoblots, suggesting the presence of D2(L) receptor monomers and dim ers. Both species were purified by immunoprecipitation from digitonin- solubilized preparation of cells expressing D2(L) receptor prelabeled with P-32(i) or [H-3]- palmitate. These results constitute the first d irect evidence for D2(L) receptor phosphorylation and palmitoylation.