Byung-Chang Suh

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To resolve the controversy about messengers regulating KCNQ ion channels during phospholipase C-mediated suppression of current, we designed translocatable enzymes that quickly alter the phosphoinositide composition of the plasma membrane after application of a chemical cue. The KCNQ current falls rapidly to zero when phosphatidylinositol 4,5-bisphosphate(More)
Suppression of M current channels by muscarinic receptors enhances neuronal excitability. Little is known about the molecular mechanism of this inhibition except the requirement for a specific G protein and the involvement of an unidentified diffusible second messenger. We demonstrate here that intracellular ATP is required for recovery of KCNQ2/KCNQ3(More)
We have further tested the hypothesis that receptor-mediated modulation of KCNQ channels involves depletion of phosphatidylinositol 4,5-bisphosphate (PIP2) by phosphoinositide-specific phospholipase C (PLC). We used four parallel assays to characterize the agonist-induced PLC response of cells (tsA or CHO cells) expressing M1 muscarinic receptors:(More)
Phosphatidylinositol 4,5-bisphosphate (PIP2) is a minority phospholipid of the inner leaflet of plasma membranes. Many plasma membrane ion channels and ion transporters require PIP2 to function and can be turned off by signaling pathways that deplete PIP2. This review discusses the dependence of ion channels on phosphoinositides and considers possible(More)
Phosphatidylinositol 4,5-bisphosphate is a signaling phospholipid of the plasma membrane that has a dynamically changing concentration. In addition to being the precursor of inositol trisphosphate and diacylglycerol, it complexes with and regulates many cytoplasmic and membrane proteins. Recent work has characterized the regulation of a wide range of ion(More)
Receptor-mediated modulation of KCNQ channels regulates neuronal excitability. This study concerns the kinetics and mechanism of M1 muscarinic receptor-mediated regulation of the cloned neuronal M channel, KCNQ2/KCNQ3 (Kv7.2/Kv7.3). Receptors, channels, various mutated G-protein subunits, and an optical probe for phosphatidylinositol 4,5-bisphosphate (PIP2)(More)
Modulation of voltage-gated Ca(2+) channels controls activities of excitable cells. We show that high-voltage activated Ca(2+) channels are regulated by membrane phosphatidylinositol 4,5-bisphosphate (PIP(2)) with different sensitivities. Plasma membrane PIP(2) depletion by rapamycin-induced translocation of an inositol lipid 5-phosphatase or by a(More)
Activity of KCNQ (Kv7) channels requires binding of phosphatidylinositol 4,5-bisphosphate (PIP(2)) from the plasma membrane. We give evidence that Mg(2+) and polyamines weaken the KCNQ channel-phospholipid interaction. Lowering internal Mg(2+) augmented inward and outward KCNQ currents symmetrically, and raising Mg(2+) reduced currents symmetrically.(More)
Phosphoinositides are a family of minority acidic phospholipids in cell membranes. Their principal role is instructional: they interact with proteins. Each cellular membrane compartment uses a characteristic species of phosphoinositide. This signature phosphoinositide attracts a specific complement of functionally important, loosely attached peripheral(More)
Phosphoinositides serve as signature motifs for different cellular membranes and often are required for the function of membrane proteins. Here, we summarize clear evidence supporting the concept that many ion channels are regulated by membrane phosphoinositides. We describe tools used to test their dependence on phosphoinositides, especially(More)