Sato Yoko, Hosoo Yoshihiro, Sakaguchi Masao, Uozumi Nobuyuki
Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
Biosci Biotechnol Biochem. 2003 Apr;67(4):923-6. doi: 10.1271/bbb.67.923.
Voltage-dependent K+ channels consist of a voltage-sensing region and a pore-forming region. Here we have identified the negative residues of the second transmembrane segment in the plant voltage-dependent K+ channel, KAT1, which involves the function of voltage sensing. Point mutations at D95 and D105 but not D89 and D116 failed to complement the K+ uptake deficient properties of the mutant yeast. In vitro translation and translocation experiments showed that the membrane integration of the third and fourth segments involving voltage sensor were impaired by the replacement of D95 or D105 by serine. These data show that both the residues play a crucial role in the membrane topogenesis of the voltage sensor in KAT1.
电压依赖性钾通道由电压感应区和孔形成区组成。在这里，我们已经确定了植物电压依赖性钾通道KAT1中第二个跨膜片段的负性残基，其涉及电压感应功能。D95和D105处的点突变而非D89和D116处的点突变未能补充突变酵母的钾离子吸收缺陷特性。体外翻译和转运实验表明，涉及电压传感器的第三和第四片段的膜整合因丝氨酸取代D95或D105而受损。这些数据表明，这两个残基在KAT1电压传感器的膜拓扑形成中都起着关键作用。
