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Structure—Function Studies of the Eighth Hydrophobic Domain of a Serotonin Receptor
Author(s) -
Hurley Joyce H.,
Bloem Laura J.,
Pavalko Fred,
Liu Jian,
Tian Mingting,
Simon Jay R.,
Yu Lei
Publication year - 1999
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1999.0720413.x
Subject(s) - receptor , 5 ht5a receptor , biology , microbiology and biotechnology , g protein coupled receptor , enzyme linked receptor , 5 ht receptor , mutant , transmembrane domain , biochemistry , insulin like growth factor 2 receptor , chemistry , biophysics , serotonin , gene , insulin like growth factor 1 receptor , growth factor
: The most prominent structural feature of the Gprotein‐coupled receptor superfamily is their seven hydrophobic domains, whichare postulated to form membrane‐spanning α helices. Some members of theG protein‐coupled receptor family, specifically several serotonin (5‐HT)receptors, possess eight hydrophobic domains. The importance of this extrahydrophobic domain, located at the N terminus of the receptor, is unknown.This question was addressed by deleting the extra hydrophobic region from the5‐HT 2C receptor and comparing its function and topology with thoseof the wild‐type receptor. Immunofluorescence microscopy was used to determinethe location of the N terminus of the epitope‐tagged wild‐type and mutantreceptors. The N terminus of both receptors was extracellular, suggesting thatthe extra hydrophobic domain does not change the topology of this receptor andis unlikely to be a membrane‐spanning α helix. Radioligand‐bindingstudies in transfected cells and expression studies in Xenopus oocytes demonstrated that seven hydrophobic domains were sufficient for normal function in these assays. Interestingly, the mutant receptor, now containing seven hydrophobic domains, is expressed at higher levels in transfected cells than the wild‐type receptor containing eight hydrophobic domains, suggesting that the extra hydrophobic domain does impact the activity of this receptor by regulating its expression.