Fink M, Duprat F, Heurteaux C, Lesage F, Romey G, Barhanin J, Lazdunski M
Institut de Pharmacologie Moléculaire et Cellulaire, CNRS, Valbonne, France.
FEBS Lett. 1996 Jan 2;378(1):64-8. doi: 10.1016/0014-5793(95)01388-1.
Chimeras have been constructed using three different fragments (N-terminal, central and C-terminal) of IRK3, a constitutive inward rectifier K+ channel subunit, and GIRK2, a G-protein activated inward rectifier K+ channel subunit and have been coinjected into Xenopus oocytes together with IRK3 or IRK1 (another constitutive inward rectifier) cRNA. Both IRK1 and IRK3 expression was inhibited by coinjection with chimeras containing a N-terminal fragment of IRK3 suggesting that subunits of K+ channels in the IRK family form a functional multimeric assembly where the N-terminal end has an important role. In situ hybridization shows that IRK1 and IRK3 are coexpressed in the same areas of the brain and probably in the same cells. Taken together both the localization and the oocyte expression results suggest that not only homomultimeric IRK1 or homomultimeric IRK3 assemblies take place but that heteromultimeric IRK1/IRK3 assemblies are also formed.
嵌合体已利用内向整流钾离子通道亚基IRK3的三个不同片段（N端、中间和C端）以及G蛋白激活的内向整流钾离子通道亚基GIRK2构建而成，并已与IRK3或IRK1（另一种组成型内向整流器）的cRNA一起共注射到非洲爪蟾卵母细胞中。与含有IRK3 N端片段的嵌合体共注射时，IRK1和IRK3的表达均受到抑制，这表明IRK家族中钾离子通道的亚基形成了功能性多聚体组装，其中N端起着重要作用。原位杂交显示IRK1和IRK3在大脑的相同区域共表达，可能也在相同细胞中共表达。综合定位和卵母细胞表达结果表明，不仅会形成同型多聚体IRK1或同型多聚体IRK3组装，还会形成异型多聚体IRK1/IRK3组装。
