Size of side-chain at channel pore mouth affects Ca(2+) block of P2X(2) receptor.
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.
Nakazawa
Ken
K
Cellular and Molecular Pharmacology Section, National Institute of Health Sciences, 1-18-1 Kamiyoga, Segataya, Tokyo, 158-8501, Japan. nakazawa@nihs.go.jp
Sawa
Hideaki
H
Ojima
Hiloe
H
Ishii-Nozawa
Reiko
R
Takeuchi
Koichi
K
Ohno
Yasuo
Y
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
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