REGULATION OF PHOSPHATASE CONTROL ION CHANNEL FUNCTION

描述(改编自摘要)可逆磷酸化是一种 激素和神经递质调节离子的重要机制 频道。尽管关于磷酸化的激酶已经知道了很多 离子通道，人们对逆转这一过程的磷酸酶知之甚少 进程。申请人的长期目标是确定如何采取行动 离子通道上的丝氨酸/苏氨酸磷酸酶受到控制。在这项提案中，有两个 控制离子通道磷酸酶的调节机制将是 研究：磷脂第二步的磷酸化和直接激活 信使。 申请人发现，在体外，蛋白激酶C的磷酸化 大鼠脑内钠通道上的位点减少去磷酸化 通道上不同的cAMP依赖的磷酸化位点。此外, 突触体中蛋白激酶C的激活导致 CAMP依赖的磷酸化位点的通道磷酸化。在……里面 突触体，蛋白激酶C可能潜在地控制通道 通过作用于通道本身或直接作用于通道而去磷酸化 磷酸酶的磷酸化和抑制。他们将决定 这些过程中的每一种对钠通道的调节作用 突触体内的去磷酸化。 在钙激活钾通道的情况下，证据表明 神经肽激素心钠素和生长抑素 通过激活丝氨酸/苏氨酸磷酸酶来刺激这些通道。心房 利钠因子通过cGMP和cGMP依赖的蛋白激酶发挥作用，而 生长抑素通过花生四烯酸的释放起作用。这些观察结果表明 Ser/Thr磷酸酶受第二种基因控制的可能性 信使cGMP和花生四烯酸或其代谢物之一。这个 调查人员将确定两种蛋白质丝氨酸/酪氨酸磷酸酶PP2A 或PP5，通过以下途径介导钙依赖性钾通道激活 心钠素或生长抑素，以及这些磷酸酶 是cGMP依赖的细胞内磷酸化或脂质的靶点 激活。 这些研究加在一起将增加我们对 离子通道上的丝氨酸/苏氨酸磷酸酶受到控制。此外，他们还将 揭示与两个离子通道的调制有关的重要细节 在神经元的兴奋和分泌中起关键作用。

DESCRIPTION (adapted from abstract) Reversible phosphorylation is an important mechanism by which hormones and neurotransmitters modulate ion channels. Although much is known concerning the kinases that phosphorylate ion channels, far less is known about the phosphatases that reverse this process. The applicants' long term goal is to determine how the action of ser/thr phosphatases on ion channels is controlled. In this proposal, two regulatory mechanisms that control ion channel phosphatases will be investigated: phosphorylation and direct activation by a lipid second messenger. The applicants have found that in vitro phosphorylation of protein kinase C sites on rat brain sodium channels decreases the dephosphorylation of distinct cAMP-dependent phosphorylation sites on channels. In addition, activation of protein kinase C in synaptosomes leads to an increase in channel phosphorylation at cAMP-dependent phosphorylation sites. In synaptosomes, protein kinase C may potentially control channel dephosphorylation by its action on channels themselves or by direct phosphorylation and inhibition of phosphatases. They will determine the contribution of each of these processes regulating sodium channel dephosphorylation in synaptosomes. In the case of calcium-activated potassium channels, evidence suggests that the neuropeptide hormones atrial natriuretic factor and somatostatin each stimulate these channels by activating a ser/thr phosphatase. Atrial natriuretic factor acts via cGMP and cGMP-dependent protein kinase, whereas somatostatin acts via arachidonic acid release. These observations suggest the possibility that ser/thr phosphatases are controlled by the second messenger cGMP and arachidonic acid or one of its metabolites. The investigators will determine whether two protein ser/thr phosphatases, PP2A or PP5, mediate the activation of calcium-dependent potassium channels by atrial natriuretic factor or somatostatin, and whether these phosphatases are intracellular targets for cGMP-dependent phosphorylation or lipid activation. These studies together will increase our understanding of how the action of ser/thr phosphatases on ion channels is controlled. In addition, they will uncover important details concerning the modulation of two ion channels that play key roles in neuronal excitation and secretion.