TY - JOUR
T1 - A ring of uncharged polar amino acids as a component of channel constriction in the nicotinic acetylcholine receptor
AU - Imoto, Keiji
AU - Konno, Takashi
AU - Nakai, Junichi
AU - Wang, Feng
AU - Mishina, Masayoshi
AU - Numa, Shosaku
N1 - Funding Information:
n~li,tonl~~/~l(WrtC th?ãnk~ D~r ~Bert/ .sSãkm ann for help during the initial stage of this work and Ms Miwa Kuchiishi for technical assis-~ancc. This invcstigarion was supporlcd in part by research grams l’rom the Ministry of Education. Scicncc and Culture of Japan, the Mitsubishi Foundation and the Japanese Fo!mdation of Mctabaolism and Discascs.
PY - 1991/9/9
Y1 - 1991/9/9
N2 - The channel pore of the nicotinic acetylcholine receptor (AChR) has been investigated by analysing single-channel conductances of systematically mutatedTorpedo receptors expressed in Xenopus oocytes. The mutations mainly alter the size and polarity of uncharged polar amino acid residues of the acetylcholine receptor subunits positioned between the cytoplasmic ring and the extracellular ring. From the results obtained, we conclude that a ring of uncharged polar residues comprising threonine 244 of the α-subunit (αT244), βS250, γT253 and δS258 (referred to as the central ring) and the anionic intermediate ring, which are adjacent to each other in the assumed α-helical configuration of the M2-containing transmembrane segment, together form a narrow channel constriction of short length, located close to the cytoplasmic side of the membrane. Our results also suggest that individual subunits, particularly the γ-subunit, are asymmetrically positioned at the channel constriction.
AB - The channel pore of the nicotinic acetylcholine receptor (AChR) has been investigated by analysing single-channel conductances of systematically mutatedTorpedo receptors expressed in Xenopus oocytes. The mutations mainly alter the size and polarity of uncharged polar amino acid residues of the acetylcholine receptor subunits positioned between the cytoplasmic ring and the extracellular ring. From the results obtained, we conclude that a ring of uncharged polar residues comprising threonine 244 of the α-subunit (αT244), βS250, γT253 and δS258 (referred to as the central ring) and the anionic intermediate ring, which are adjacent to each other in the assumed α-helical configuration of the M2-containing transmembrane segment, together form a narrow channel constriction of short length, located close to the cytoplasmic side of the membrane. Our results also suggest that individual subunits, particularly the γ-subunit, are asymmetrically positioned at the channel constriction.
KW - Channel constriction
KW - Ionic channel
KW - Nicotinic acetylcholine receptor
KW - Single-channel recording
KW - Site-directed mutagenesis
KW - cDNA expression
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U2 - 10.1016/0014-5793(91)81068-J
DO - 10.1016/0014-5793(91)81068-J
M3 - Article
C2 - 1717313
AN - SCOPUS:0025745108
VL - 289
SP - 193
EP - 200
JO - FEBS Letters
JF - FEBS Letters
SN - 0014-5793
IS - 2
ER -