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A unique phenotype of 5‐HT 2C , agonist‐induced GTPγ 35 S binding, transferable to 5‐HT 2A and 5‐HT 2B , upon swapping intracellular regions
Author(s) -
Alberts Glen L,
Chio Christopher L,
Im Wha Bin,
Slightom Jerry L
Publication year - 2003
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0705058
Subject(s) - receptor , agonist , hek 293 cells , intracellular , g protein , 5 ht receptor , inositol phosphate , gtp' , g protein coupled receptor , gq alpha subunit , binding site , biology , chemistry , biochemistry , inositol , microbiology and biotechnology , serotonin , enzyme
The human 5‐HT 2C receptor, when expressed heterologously in various mammalian cell lines (HEK293, SH‐EP and NIH‐3T3) at various receptor densities (6 to 45 pmol mg −1 protein), mediates robust agonist‐induced GTPγ 35 S binding from coupling to G i subtypes of G proteins, in addition to G q/11 . Such a phenotype, however, was not seen with the human 5‐HT 2A and 5‐HT 2B receptors, indicating their common pathway with 5‐HT 2C limited to G q/11 , not including G i . Because intracellular regions are largely responsible for signalling pathways, we prepared the chimeras of the 5‐HT 2A and 5‐HT 2B receptors where the second and third intracellular loops, and the C‐terminal region were replaced with the 5‐HT 2C counterparts. The chimeras showed robust agonist‐induced GTPγ 35 S binding. Relative intrinsic efficacies of agonists from the GTPγ 35 S binding were nearly identical to the reported values for their parent receptors as measured with Ca 2+ or [ 3 H]‐inositol phosphate accumulation. Also the chimeras displayed the same ligand‐binding properties as the parent receptors. We conclude that the phenotype of agonist‐induced GTPγ 35 S binding is unique to 5‐HT 2C among the 5‐HT 2 receptor family, and is transferable to 5‐HT 2A and 5‐HT 2B , upon swapping intracellular sequences, without altering their receptor pharmacology.British Journal of Pharmacology (2003) 138 , 427–434. doi: 10.1038/sj.bjp.0705058