title: Amino acid substitutions from an indispensable disulfide bond affect P2X2 receptor activation.
abstract: The roles of six amino acid residues downward from an extracellular disulfide bond involving Cys(224) in rat P2X(2) receptor were examined. When Cys(224) or Pro(225) was replaced with alanine, the responsiveness to ATP was lost. When Ile(226) was replaced with other hydrophobic amino acids, the responsiveness to ATP was reduced or abolished. When Phe(227) was replaced with leucine or isoleucine, the responsiveness to ATP was abolished. The responsiveness to ATP was moderately decreased with the alanine-substitution for Arg(228) and it was markedly decreased with the alanine-substitution for Leu(229). As for the alanine-substitution for Gly(230), the sensitivity was changed, but the maximal response to ATP was not reduced. The results suggested that a precise structure is required for amino acid residues close to the disulfide bond and, in general, the amino acid residues at odd number positions and those closer to the disulfide bond are more influential to the ATP responsiveness.
authors.affiliation: Cellular and Molecular Pharmacology Section, Division of Pharmacology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya, Tokyo, Japan. nakazawa@nihs.go.jp
authors.forename: Ken
authors.initials: K
authors.lastname: Nakazawa
authors.forename: Hiloe
authors.initials: H
authors.lastname: Ojima
authors.forename: Reiko
authors.initials: R
authors.lastname: Ishii-Nozawa
authors.forename: Koichi
authors.initials: K
authors.lastname: Takeuchi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ohno
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000465:Algorithms; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D004220:Disulfides; D015151:Immunoblotting; D007473:Ion Channels / Q000378:metabolism; D007700:Kinetics; D016296:Mutagenesis; D009865:Oocytes / Q000378:metabolism; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000187:drug effects*; D058476:Receptors, Purinergic P2X2; D014981:Xenopus
chemical_list: D004220:Disulfides; D007473:Ion Channels; C546403:P2rx2 protein, rat; D018048:Receptors, Purinergic P2; D058476:Receptors, Purinergic P2X2; D000255:Adenosine Triphosphate