Expression of dopamine D-3 receptor dimers and tetramers in brain and in transfected cells
Expression of dopamine D-3 receptor dimers and tetramers in brain and in transfected cells
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DOI：
10.1074/jbc.272.46.29229
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发表时间：
1997-11-14
影响因子：
4.8
通讯作者：
Schmauss, C
中科院分区：
文献类型：
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作者：
Nimchinsky, EA;Hof, PR;Schmauss, C
在脑组织和稳定转染的GH3细胞中研究多巴胺D-3受体蛋白的表达和特性，采用单克隆抗体进行免疫沉淀和免疫印迹实验。从灵长类动物和啮齿动物的脑组织中获得的免疫沉淀含有低分子量的D-3蛋白和一个或两个较大的蛋白物种，其分子质量是低分子量蛋白的整数倍，因此似乎是由D-3单体的二聚化和四聚化产生的。在稳定表达D-3的大鼠GH3细胞中，主要表达的D-3免疫反应性为单体。然而，当截断的D-3样蛋白（命名为D-3nf）在这些细胞中共表达时，在表达D-3的GH3细胞中也可以看到具有与脑中表达的相似的电泳迁移性的多聚体D-3受体物种。D-3和D-3nf特异性抗体的免疫沉淀实验结果表明，从脑中提取的高阶D-3蛋白和D-3/D-3nf双转染物也含有D-3nf免疫反应性，免疫细胞化学研究表明，D-3和D-3nf免疫反应性在猴和大鼠皮层神经元中表达有很大的重叠。总之，这些数据显示了体内低聚D-3受体蛋白的表达，它们表明至少一些低聚物是含有D-3和截断的D-3nf蛋白的异聚蛋白复合物。
The expression and characteristics of the dopamine D-3 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 D-3 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 D-3 monomer, Whereas D-3 receptor multimers were found to be abundantly expressed in brain, the major D-3 immunoreactivity expressed in stable D-3-expressing rat GH3 cells was found to be a monomer, However, multimeric D-3 receptor species with electrophoretic mobilities similar to those expressed in brain were also seen in D-3-expressing GH3 cells when a truncated D-3-like protein (named D-3nf) was coexpressed in these cells, Furthermore, results from immunoprecipitation experiments with D-3- and D-3nf-specific antibodies show that the higher order D-3 proteins extracted from brain and D-3/D-3nf double transfectants also contain D-3nf immunoreactivity, and immunocytochemical studies show that the expression of D-3 and D-3nf immunoreactivities overlaps substantially in monkey and rat cortical neurons. Altogether, these data show oligomeric D-3 receptor protein expression in vivo and they suggest that at least some of these oligomers are heteroligomeric protein complexes containing D-3 and the truncated D-3nf protein.