Retrovirus-mediated expression of the GalR1 galanin receptor: Implication for efficient stable expression of functional G protein-coupled receptors

The rat GalR1 galanin receptor was used as a prototypic G protein-coupled r eceptor to test the feasibility of heterologous expression in a retrovirus- based system. The system utilizes an independent retroviral vector pMX, a v irus-packaging cell line BOSC23 and a pre-B cell line BA/F3 as the host for expression. A polyclonal cell population that expresses high ligand affini ty (K-D = 0.18 nM) and high level (7 pmol/mg) of GalR1 was generated within days with no drug sensitivity-based selection. The expression represented a 20-fold increase over the expression level of GalR1 achieved in CHO cells . The affinity of galanin for the expressed receptor was decreased by 19-fo ld in the presence of GTP-gamma-S, suggesting that the expression system ca n produce active galanin receptor functionally coupled to G proteins. The f ast and efficient method to generate stable cell lines and to prepared larg e quantities of receptors may provide a general application for expression of other G protein-coupled receptors.