Dunne M J, Petersen O H
Pflugers Arch. 1986 Nov;407(5):564-5. doi: 10.1007/BF00657518.
K+ channels that can be inhibited by intracellular ATP have been found in many different cell types. In the insulin-secreting pancreatic islet cells these channels are of crucial importance for stimulus-secretion coupling as glucose stimulation closes the ATP-sensitive channels which leads to depolarization and firing of Ca2+ action potentials. We now demonstrate that nucleotides other than ATP also influence the gating of these K+ channels. In contrast to the action of ATP, GTP (10 microM-1 mM) and GDP (100 microM to 1 mM) evoke dose-dependent channel activation and this effect is immediately reversible. Phosphorylation is not directly involved as non-hydrolysable GTP- and GDP-analogues also evoke channel opening. ATP reversibly inhibits opening of the GTP- or GDP-activated K+ channels.
在许多不同类型的细胞中都发现了可被细胞内ATP抑制的钾离子通道。在分泌胰岛素的胰岛细胞中，这些通道对于刺激-分泌偶联至关重要，因为葡萄糖刺激会关闭ATP敏感性通道，从而导致去极化并引发钙离子动作电位。我们现在证明，除ATP之外的核苷酸也会影响这些钾离子通道的门控。与ATP的作用相反，GTP（10微摩尔至1毫摩尔）和GDP（100微摩尔至1毫摩尔）会引起剂量依赖性的通道激活，并且这种效应是立即可逆的。由于不可水解的GTP和GDP类似物也会引起通道开放，因此磷酸化并不直接参与其中。ATP可逆地抑制GTP或GDP激活的钾离子通道的开放。
