TBAK-1 and TASK-1, two-pore K+ channel subunits:: kinetic properties and expression in rat heart
TBAK-1 and TASK-1, two-pore K+ channel subunits:: kinetic properties and expression in rat heart
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DOI：
10.1152/ajpheart.1999.277.5.h1669
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发表时间：
1999-11-01
影响因子：
4.8
通讯作者：
Kim, D
中科院分区：
文献类型：
--
作者：
Kim, Y;Bang, H;Kim, D
TEAK-I和ASK-1，双孔K+通道亚基：动力学特性和在大鼠心脏中的表达。Am. J. Physiol.277（Heart Circ. 46）：H1669-H1678，1999。- 哺乳动物K+通道亚基（TBAK-1/ASK-1）含有两个孔结构域和四个跨膜片段，其mRNA在心脏中高度表达。除了TEAK-I的NH 2末端中的另外9个氨基酸之外，TEAK-I和TASK-1是相同的。我们研究了它们的动力学特性、pH敏感性和区域心脏mRNA表达，并确定是否存在具有相似动力学特性的天然心脏K+通道。当TBAK-1或ASK-1在COS-7细胞中瞬时表达时，观察到非时间和电压依赖性的全细胞电流。在140 mM细胞外K+中，在-80 mV下，TEAK-I和Task-I的单通道电导分别为14.6 +/- 1.0和13.8 +/- 2.8 pS，平均开放时间分别为0.8 +/- 0.1和0.6 +/- 0.1 ms。TBAK-1和TASK-1都对细胞外pH高度敏感，从7.2降至6.4时，它们的开放概率（P-o）分别降低了81 +/-14%和80 +/-16%，而细胞内pH从7.2降至6.4时，P-o分别降低了42 +/-10%和47 +/-12%。TBAK-1/ASK-1 mRNA在大鼠心脏的所有区域中表达，在右心房中的表达水平最高。在大鼠心房和心室肌细胞中发现了一个14 pS的K+通道，其动力学性质与TBAK-1/ASK-1相似。这些结果表明TBAK-1/ASK-1代表大鼠心脏中的功能性天然K+通道。
TEAK-I and TASK-1, two-pore K+ channel subunits: kinetic properties and expression in rat heart. Am. J. Physiol. 277 (Heart Circ. Physiol. 46): H1669-H1678, 1999. -A mammalian K+ channel subunit (TBAK-1/TASK-1) containing two pore domains and four transmembrane segments and whose mRNA is highly expressed in the heart has been cloned recently. TEAK-I and TASK-1 are identical except for the additional nine amino acids in the NH2 terminus of TEAK-I. We examined their kinetic properties, pH sensitivity, and regional cardiac mRNA expression and determined whether a native cardiac K+ channel with similar kinetic properties was present. When TBAK-1 or TASK-1 was transiently expressed in COS-7 cells, time- and voltage-independent whole cell currents were observed. Single-channel conductances of TEAK-I and TASK-1 were 14.6 +/- 1.0 and 13.8 +/- 2.8 pS, respectively, at -80 mV in 140 mM extracellular K+, and the mean open times were 0.8 +/- 0.1 and 0.6 +/- 0.1 ms, respectively. Both TBAK-1 and TASK-1 were highly sensitive to extracellular pH such that a decrease from 7.2 to 6.4 reduced their open probability (P-o) by 81 +/- 14% and 80 +/- 16%, whereas a decrease in intracellular pH from 7.2 to 6.4 reduced the P-o by 42 +/- 10% and 47 +/- 12%, respectively. TBAK-1/TASK-1 mRNA was expressed in all regions of the rat heart, with the highest level of expression in the right atrium. A 14-pS K+ channel with kinetic properties similar to those of TBAK-1/TASK-1 was identified in rat atrial and ventricular cells. These results indicate that TBAK-1/TASK-1 represents a functional native K+ channel in the rat heart.