SIMILAR LIGAND-BINDING IN RECOMBINANT HUMAN ALPHA-2 C2-ADRENOCEPTORS PRODUCED IN MAMMALIAN, INSECT AND YEAST-CELLS

Ligand binding properties were investigated in recombinant human alpha 2C2-adrenoceptors expressed in three different host systems: Shionogi S115 mouse mammary tumour cells, Spodoptera frugiperda Sf9 insect cell s and Saccharomyces cerevisiae yeast cells. The expected 43 kDa alpha2 C2 Protein was visualized with immunoblotting using a polyclonal alpha 2C2-receptor antibody. [H-3]Rauwolscine binding in cell homogenates or membranes (B(max) 3-11 pmol/mg protein; K(d) approximately 5.5 nM) wa s inhibited by prazosin, oxymetazoline, RX821002, chlorpromazine and ( -)-noradrenaline with and without the GTP-analogue Gpp(NH)p with simil ar K(i) values in the different host systems. This indicates that alph a2C2-adrenoceptors retain their binding characteristics irrespective o f the host environment.