A highly conserved tryptophane residue indispensable for cloned rat neuronal P2X receptor activation.
The role of a tryptophane residue (Trp(256)) in the extracellular loop of a neuronal P2X receptor clone (P2X(2) receptor/channel) was investigated using site-directed mutagenesis and Xenopus oocyte expression. When Trp(256) was replaced with leucine, serine or phenylalanine (W256L, W256S or W256F), a current response to adenosine triphosphate (ATP) mediated through the P2X2 receptor/channel was abolished. When replaced with tyrosine (W256Y), the response was not abolished, but a reduced current response to ATP was observed. The insertion of a tryptophane residue in W256L at positions close to position 256 failed to recover the responsiveness to ATP. These results suggest that an amino acid residue with a side chain of an aromatic ring with a hydroxy group (tryptophane or tyrosine) is necessary exactly at position 256 for P2X(2) receptor/channel activation.
Nakazawa
Ken
K
Cellular and Molecular Pharmacology Section, Division of Pharmacology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya, Tokyo 158-8501, Japan. nakazawa@nihs.go.jp
Ojima
Hiloe
H
Ohno
Yasuo
Y
D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000595:Amino Acid Sequence / Q000187:drug effects / Q000235:genetics; D000818:Animals; D002478:Cells, Cultured; D002999:Clone Cells / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D007473:Ion Channels / Q000737:chemistry / Q000187:drug effects / Q000235:genetics; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000187:drug effects / Q000235:genetics*; D009420:Nervous System / Q000166:cytology / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009865:Oocytes; D010649:Phenylalanine / Q000737:chemistry / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics; D058469:Receptors, Purinergic P2X; D009435:Synaptic Transmission / Q000502:physiology*; D014364:Tryptophan / Q000737:chemistry* / Q000235:genetics; D014982:Xenopus laevis
D007473:Ion Channels; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D010649:Phenylalanine; D014364:Tryptophan; D000255:Adenosine Triphosphate