Pribilla I, Takagi T, Langosch D, Bormann J, Betz H
Zentrum für Molekulare Biologie, Universität Heidelberg, Germany.
EMBO J. 1992 Dec;11(12):4305-11. doi: 10.1002/j.1460-2075.1992.tb05529.x.
Purified preparations of the inhibitory glycine receptor (GlyR) contain alpha and beta subunits, which share homologous primary structures and a common transmembrane topology with other members of the ligand-gated ion channel superfamily. Here, a beta subunit-specific antiserum was shown to precipitate the [3H]strychnine binding sites localized on alpha subunits from membrane extracts of both rat spinal cord and mammalian cells co-transfected with alpha and beta cDNAs. Further, inhibition of alpha homo-oligomeric GlyRs by picrotoxinin, a non-competitive blocker of ion flow, was reduced 50- to 200-fold for alpha/beta hetero-oligomeric receptors generated by cotransfection. Site-directed mutagenesis identified residues within the second predicted transmembrane segment (M2) of the beta subunit as major determinants of picrotoxinin resistance. These data implicate the M2 segment in blocker binding to and lining of the GlyR chloride channel.
纯化的抑制性甘氨酸受体（GlyR）制剂包含α和β亚基，它们与配体门控离子通道超家族的其他成员具有同源的一级结构和共同的跨膜拓扑结构。在此，一种β亚基特异性抗血清被证明能从大鼠脊髓和共转染了α和β cDNA的哺乳动物细胞的膜提取物中沉淀出位于α亚基上的[3H]士的宁结合位点。此外，对于通过共转染产生的α/β异源寡聚体受体，离子流的非竞争性阻断剂印防己毒素对α同源寡聚体GlyRs的抑制作用降低了50至200倍。定点诱变确定β亚基第二个预测跨膜片段（M2）内的残基是印防己毒素抗性的主要决定因素。这些数据表明M2片段参与了阻断剂与GlyR氯离子通道的结合及通道内衬。
