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Analysis of Domains for D2 Dopamine Receptor‐G Protein Coupling by Minigene Expression
Author(s) -
Kendall Ryan T.,
Senogles Susan E.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a917-c
Subject(s) - 5 ht5a receptor , receptor , enzyme linked receptor , biology , microbiology and biotechnology , intracellular , dopamine receptor d2 , minigene , 5 ht7 receptor , gene isoform , biochemistry , alternative splicing , 5 ht receptor , gene , serotonin
We have analyzed the two isoforms of the D 2 dopamine receptor, D 2 long (D 2L ) and D 2 short (D 2S ), which differ only by a 29‐amino acid insertion in the third cytoplasmic loop. Differences in physiological function have been shown for the two receptors. Using minigene expression, we found that expression of specific intracellular regions from the D 2 receptors blocked receptor‐mediated inhibition of forskolin‐stimulated adenylate cyclase. From these studies, we conclude that the N‐terminal portion of the third intracellular loop is critical for D 2L receptor signaling and that the C‐terminal portion of the third intracellular loop is critical for D 2S receptor signaling. The alternatively‐spliced sequence appears to have no function other than to alter the conformation of the third intracellular loop (Kendall and Senogles, Neuroscience Letters 2005 in press ). When adjacent cytoplasmic regions of the receptors where analyzed in the same manner, it was found that the receptor's C terminus antagonized the D 2L receptor but not the D 2S receptor. Moreover, the second intracellular loop was found to be critical for D 2S receptor signaling but not D 2L receptor signaling. The most straightforward explanation would be that the D 2 receptor's third intracellular loop is coiled to form G protein contact sites. These data strengthen our understanding of the distinct mechanistic function of each D 2 receptor isoform. This work was supported by United States Public Health Service Grant NS28811 (to S.E.S.) and by a grant from the University of Tennessee Center of Genomics and Bioinformatics.