Chapman C G, Meadows H J, Godden R J, Campbell D A, Duckworth M, Kelsell R E, Murdock P R, Randall A D, Rennie G I, Gloger I S
Biotechnology and Genetics, SmithKline Beecham Pharmaceuticals, New Frontiers Science Park, Third Avenue, Essex CM19 5AW, Harlow, UK.
Brain Res Mol Brain Res. 2000 Oct 20;82(1-2):74-83. doi: 10.1016/s0169-328x(00)00183-2.
We have isolated, by degenerate PCR, a complementary DNA encoding a novel two pore domain potassium channel. This is the 7th functional member of the human tandem pore domain potassium channel family to be reported. It has an open reading frame of 1.125 kb and encodes a 374 amino acid protein which shows 62% identity to the human TASK-1 gene: identity to other human members of the family is 31-35% at the amino acid level. We believe this gene to be human TASK-3, the ortholog of the recently reported rat TASK-3 gene: amino acid identity between the two is 74%. 'Taqman' mRNA analysis demonstrated a very specific tissue distribution pattern, showing human TASK-3 mRNA to be localised largely in the cerebellum, in contrast rat TASK-3 was reported to be widely distributed. We have shown by radiation hybrid mapping that human TASK-3 can be assigned to chromosome 8q24.3. Human TASK-3 was demonstrated to endow Xenopus oocytes with a negative resting membrane potential through the presence of a large K(+) selective conductance. TASK-3 is inhibited by extracellular acidosis with a mid-point of inhibition around pH 6. 5, supporting the predictions from the sequence data that this is a third human TASK (TWIK-related acid sensitive K(+) channel) gene.
我们通过简并PCR分离出了一个编码新型双孔结构域钾通道的互补DNA。这是已报道的人类串联孔结构域钾通道家族的第7个功能成员。它有一个1.125 kb的开放阅读框，编码一个374个氨基酸的蛋白质，该蛋白质与人类TASK-1基因有62%的同源性：在氨基酸水平上与该家族其他人类成员的同源性为31%-35%。我们认为该基因是人类TASK-3，即最近报道的大鼠TASK-3基因的直系同源基因：两者之间的氨基酸同源性为74%。“Taqman”mRNA分析显示出非常特异的组织分布模式，表明人类TASK-3 mRNA主要定位于小脑，相比之下，据报道大鼠TASK-3分布广泛。我们通过辐射杂种图谱分析表明，人类TASK-3可定位于8号染色体q24.3。通过存在大的K(+)选择性电导，证明人类TASK-3赋予非洲爪蟾卵母细胞负的静息膜电位。TASK-3受到细胞外酸中毒的抑制，抑制中点约为pH 6.5，支持序列数据的预测，即这是第三个人类TASK（TWIK相关酸敏感K(+)通道）基因。
