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Isolating and characterizing three alternatively spliced mu opioid receptor variants: mMOR‐1A, mMOR‐1 O , and mMOR‐1P
Author(s) -
Xu Jin,
Xu Mingming,
Bolan Elizabeth,
Gilbert AnnieKim,
Pasternak Gavril W.,
Pan YingXian
Publication year - 2014
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.21727
Subject(s) - splice , chinese hamster ovary cell , alternative splicing , rna splicing , agonist , biology , gene , μ opioid receptor , transmembrane protein , transmembrane domain , microbiology and biotechnology , receptor , genetics , messenger rna , rna
Extensive alternative pre‐mRNA splicing of the mu opioid receptor gene, OPRM1 , has demonstrated an array of splice variants in mice, rats and humans. Three classes of splice variants have been identified: full‐length seven transmembrane (TM) domain variants with C‐terminal splicing, truncated 6TM variants and single TM variants. The current studies isolates and characterizes an additional three full‐length C‐terminal splice variants generated from the mouse OPRM1 gene: mMOR‐1A, mMOR‐1 O , and mMOR‐1P. Using RT‐qPCR, we demonstrated differential expression of these variants' mRNAs among selected brain regions, supporting region‐specific alternative splicing. When expressed in Chinese Hamster Ovary cells, all the variants displayed high mu binding affinity and selectivity with subtle differences in the affinities toward some agonists. [ 35 S]γGTP binding assays revealed marked differences in agonist‐induced G protein activation in both potency and efficacy among the variants. Together with the previous studies of mu agonist‐induced phosphorylation and internalization in several carboxyl terminal splice variants, the current studies further suggest the existence of biased signaling of various agonists within each individual variant and/or among different variants. Synapse 68:144–152, 2014 . © 2013 Wiley Periodicals, Inc.