Glycosylation influences gating and pH sensitivity of IsK
Glycosylation influences gating and pH sensitivity of IsK
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DOI：
10.1007/s002320001100
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发表时间：
2000-09-01
影响因子：
2.4
通讯作者：
Mitchell, KE
中科院分区：
文献类型：
--
作者：
Freeman, LC;Lippold, JJ;Mitchell, KE
KvLQT1和水貂亚基共同组装形成I-SK通道，含有潜在的N-糖基化位点。为探讨糖基化在通道功能中的作用，将人KvLQT1(HKvLQT1)基因与大鼠(RminK)或人水貂(HminK)基因联合瞬时导入中国仓鼠卵巢细胞系(Lec-1)及其亲本细胞(Pro-5)。两种细胞系均表达功能性KvLQT1和I-SK电流，但Pro-5的幅度大于转染hKvLQT1和hKvLQT1/hminK的Lec-1细胞。对于I-SK，而不是KvLQT1，与Pro-5细胞相比，Lec-1细胞的激活电压依赖于更多的正电压，激活动力学较慢。研究了胞外酸化对Pro-5和Lec-1细胞重组KvLQT1和I-SK电流的影响。改变外加pH(pH(O)从7.4到6.0可显著降低Pro-5和Lec-1细胞KVLQT1电流的幅度和增加KVLQT1电流的半激活电压(V-1/2)。在Pro-5细胞中，无论rminK或hminK与hKvLQT共表达，降低pH(O)均可降低I-SK幅度而不增加V-1/2。而pH(O)从7.4改变到6.0，对Lec-1细胞的I-SK幅度无明显影响。因此，结合在水貂亚基上的低聚糖不仅影响门控特性，而且还影响I-SK的pH敏感性。
The KvLQT1 and minK subunits that coassemble to form I-sK channels, contain potential N-glycosylation sites. To examine the role of glycosylation in channel function, a Chinese hamster ovary cell line deficient in glycosylation (Lec-1) and its parental cell line (Pro-5) were transiently transfected with human KvLQT1 (hKvLQT1) cDNA, alone and in combination with the rat (rminK) or human minK (hminK) cDNA. Functional KvLQT1 and I-sK currents were expressed in both cell lines, although amplitudes were larger in Pro-5 than Lec-1 cells transfected with hKvLQT1 and hKvLQT1/hminK. For I-sK, but not KvLQT1, the voltage-dependence of activation was shifted to more positive voltages and the activation kinetics were slower in the Lec-1 compared to the Pro-5 cells. The effect of extracellular acidification on recombinant KvLQT1 and I-sK currents was investigated in Pro-5 and Lec-1 cells. Changing external pH (pH(o)) from 7.4 to 6.0 significantly decreased the amplitude and increased the half-activation voltage (V-1/2) of KVLQT1 currents in Pro-5 and Lec-1 cells. In Pro-5 cells, decreasing pH(o) reduced I-sK amplitude without increasing V-1/2 whether rminK or hminK was coexpressed with hKvLQT. In contrast, changing pH(o) from 7.4 to 6.0 did not significantly change I-sK amplitude in Lec-1 cells. Thus, oligosaccharides attached to the minK subunit affect not only the gating properties, but also the pH sensitivity of I-sK.