Mishina M, Sakimura K, Mori H, Kushiya E, Harabayashi M, Uchino S, Nagahari K
Department of Neuropharmacology, Niigata University, Japan.
Biochem Biophys Res Commun. 1991 Oct 31;180(2):813-21. doi: 10.1016/s0006-291x(05)81137-4.
Functional analysis of AMPA-selective glutamate receptor channels expressed in Xenopus oocytes from cloned cDNAs has shown that homomeric channels formed by the GluR1 subunit are permeable to Ca2+, whereas heteromeric channels composed of the GluR1 and GluR2 subunits show little permeability. Furthermore, substitution of glutamine for arginine in putative transmembrane segment M2 of the GluR2 subunit makes the heteromeric channels permeable to Ca2+. These results suggest that the GluR2 subunit plays a key role in keeping AMPA-selective glutamate receptor channels essentially impermeable to Ca2+ and that the critical determinant is the positively charged residue in M2 segment.
对从克隆的互补脱氧核糖核酸（cDNA）在非洲爪蟾卵母细胞中表达的α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）选择性谷氨酸受体通道进行的功能分析表明，由GluR1亚基形成的同聚体通道对Ca2+具有通透性，而由GluR1和GluR2亚基组成的异聚体通道则几乎没有通透性。此外，在GluR2亚基假定的跨膜片段M2中用谷氨酰胺替代精氨酸会使异聚体通道对Ca2+具有通透性。这些结果表明，GluR2亚基在使AMPA选择性谷氨酸受体通道基本上对Ca2+不具有通透性方面起关键作用，并且关键决定因素是M2片段中的带正电荷残基。
