High-efficiency expression of mammalian β-adrenergic receptors in baculovirus-infected insect cells

Infection of a clonal isolate of Spodoptera frugiperda cells (Sf9) with a baculovirus expression vector harboring the cDNA encoding the β-adrenergic receptor resulted in a high efficiency expression. At 48 hr post-infection, the level of expression of β-adrenergic receptors was ∼12 million/cell. Specific activities of crude lysates of infected Sf9 cells were ∼30 pmol/mg of protein, 5-fold greater than those of membranes of high-expressor Chinese hamster ovary cells stably transfected with an SV-40 expression vector. One liter of infected Sf9 cells expresses 20-40 nmol of receptor. Autoradiography of membranes incubated with the β-adrenergic antagonist [¹²⁵I]iodoazidobenzylpindolol, photolyzed, and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed 46,000- (presumably unglycosylated) and 48,000-M_r peptides for Sf9 cells as compared to ∼65,000-M_r for Chinese hamster ovary cells. The baculovirus Sf9 system provides high-efficiency expression of receptor sufficient to permit physicochemical analyses.