title: Size of side-chain at channel pore mouth affects Ca(2+) block of P2X(2) receptor.
abstract: Effects of amino acid replacement at the channel pore mouth of P2X(2) receptor/channel on multivalent cation channel block were investigated. When Asn(333) was replaced with various amino acid residues with neutral side chains (Gly, Ala, Val, Leu and Ile), the block by Ca(2+) was attenuated according to the sizes of the side chains. The block by La(3+) was also greatest with the Gly-substituted mutant, but this preference was not found for the block by other multivalent cations tested. The side chain at the channel pore mouth may interfere with the access of Ca(2+) block by steric hindrance.
authors.affiliation: Cellular and Molecular Pharmacology Section, National Institute of Health Sciences, 1-18-1 Kamiyoga, Segataya, Tokyo, 158-8501, Japan. nakazawa@nihs.go.jp
authors.forename: Ken
authors.initials: K
authors.lastname: Nakazawa
authors.forename: Hideaki
authors.initials: H
authors.lastname: Sawa
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; D019943:Amino Acid Substitution; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002412:Cations / Q000494:pharmacology; D003001:Cloning, Molecular; D015640:Ion Channel Gating / Q000235:genetics / Q000502:physiology; D007473:Ion Channels / Q000037:antagonists & inhibitors / Q000737:chemistry; D007811:Lanthanum / Q000494:pharmacology; D008968:Molecular Conformation; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D009865:Oocytes / Q000378:metabolism; D058919:Purinergic P2 Receptor Antagonists; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000737:chemistry* / Q000235:genetics; D058476:Receptors, Purinergic P2X2; D014981:Xenopus
chemical_list: D002412:Cations; D007473:Ion Channels; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058476:Receptors, Purinergic P2X2; D007811:Lanthanum; D000255:Adenosine Triphosphate; D002118:Calcium