Comparative analysis of the human angiotensin II type 1a receptor heterologously produced in insect cells and mammalian cells

Angiotensin II type 1a receptor (AT(1a)R) is a member of GPCR superfamily and it plays crucial roles in the regulation of blood pressure, hormone secretion and renal functions. Here, we report functional overexpression and characterization of the human AT(1a)R in insect cells using the baculovirus system and in mammalian cells using the Semliki Forest virus system. The recombinant receptor was expressed at a level of 29-32 pmol/mg and it binds to angiontensin II with high affinity (K-d = 0.98-1.1 nM). Angiotensin II stimulated accumulation of inositol phosphate and phosphorylation of MAP kinase was also observed, which indicated that the recombinant AT(1a)R could couple to endogenous G alpha(q) protein. Confocal laser scanning microscopy revealed that the recombinant receptor was predominantly localized in the plasma membrane and agonist induced internalization of the recombinant AT(1a)R was also observed. The recombinant AT(1a)R was expressed in glycosylated form and in vivo inhibition of glycosylation suppressed its surface expression. (c) 2006 Elsevier Inc. All rights reserved.