The Study Of The Relationship Between Membrane PIP₂ Hydrolysis, Intracellular Ca～(2+) Release And M Channel Function

Phosphatidylinositol 4, 5-bisphosphate (PIP₂) is extensively distributed in the interior side of the eukaryotic cell membrane. PIP₂, although a minor component of the membrane phospholipids, yet plays important roles in a wide variety of cellular processes, such as generation of second messengers, regulation of both endocytosis and exocytosis, membrane attachment to the cytoskeleton, etc.PIP₂ is a pivotal regulator in cell signaling pathway. DAG and IP₃, which are generated from PIP₂ hydrolysis by PLC, act as second messengers to activate PKC and induce intracellular Ca release, respectively. Recently, evidences are accumulating that PIP₂ per se is a second messenger involving in the regulation of N-type calcium channel and varies of voltage dependent potassium channels, including Kir and KCNQ, etc.M current or I_M, is a slow activating, non inactivating, voltage dependent, outward potassium current. It is named M current because of its suppression by muscarinic receptor activation. Great efforts have been made to elucidate the mechanism of I_M inhibition ever since its dis(?)overy almost 25 years ago by Brown and Adams. It has been found that the...