Abstract
The expression and characteristics of the dopamine D3 receptor protein were studied in brain and in stably transfected GH3 cells. Monoclonal antibodies were used for immunoprecipitation and immunoblot experiments. Immunoprecipitates obtained from primate and rodent brain tissues contain a low molecular weight D3 protein and one or two larger protein species whose molecular mass are integral multiples of the low molecular weight protein and thus appear to have resulted from dimerization and tetramerization of a D3 monomer. Whereas D3 receptor multimers were found to be abundantly expressed in brain, the major D3 immunoreactivity expressed in stable D3-expressing rat GH3 cells was found to be a monomer. However, multimeric D3 receptor species with electrophoretic mobilities similar to those expressed in brain were also seen in D3-expressing GH3 cells when a truncated D3-like protein (named D3nf) was co-expressed in these cells. Furthermore, results from immunoprecipitation experiments with D3- and D3nf-specific antibodies show that the higher-order D3 proteins extracted from brain and D3/D3nf double transfectants also contain D3nf immunoreactivity, and immunocytochemical studies show that the expression of D3 and D3nf immunoreactivities overlaps substantially in monkey and rat cortical neurons. Altogether, these data show oligomeric D3 receptor protein expression in vivo and they suggest that at least some of these oligomers are heteroligomeric protein complexes containing D3 and the truncated D3nf protein.
Highlights
The expression and characteristics of the dopamine D3 receptor protein were studied in brain and in stably transfected GH3 cells
Characterization of the Antibodies—The characterization of one of the D3 receptor antibodies used in this study has been reported previously [13]. This antipeptide antibody, which was raised against the amino terminus of the human D3 receptor (Cambio, Cambridge, UK), detected D3 immunoreactivity in immunoblot experiments using proteins extracted from rat GH3 cells that stably express the human dopamine D3 receptor under the transcriptional control of a tetracycline-responsive promotor
D3 Receptor Immunoreactivity Expressed in Stably Transfected rat GH3 Cells—The results shown in Fig. 2 motivated us to examine in more detail whether higher-order structures of the D3 protein can be detected in a single type of cell in which the level of D3 receptor expression can be controlled
Summary
The expression and characteristics of the dopamine D3 receptor protein were studied in brain and in stably transfected GH3 cells. Results from immunoprecipitation experiments with D3- and D3nf-specific antibodies show that the higher-order D3 proteins extracted from brain and D3/D3nf double transfectants contain D3nf immunoreactivity, and immunocytochemical studies show that the expression of D3 and D3nf immunoreactivities overlaps substantially in monkey and rat cortical neurons.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
