A ligan1 - cell Some gated ion channels respond to electrical signals instead of ligands Some receptor proteins are intracellular Intracellular

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ligand-gated ion channel  is a type of membrane receptor that can act as a gate when the  receptor changes shape. When a signal molecule binds as a ligand to the receptor protein, the gate opens to allow the  flow of specific ions, such as Na or Ca 2+ , through a channel in the receptor. o Binding by a ligand to the extracellular side changes the protein’s shape and opens the  channel. o When the ligand dissociates from the receptor protein, the channel closes. The change in ion concentration within the cell may directly affect the activity of the cell. Ligand-gated ion channels are very important in the nervous system. o For example, neurotransmitter molecules released at a synapse between two neurons bind as  ligands to ion channels on the receiving cell, causing the channels to open. o Ions flow in and trigger an electrical signal that propagates down the length of the receiving 
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Unformatted text preview: cell. Some gated ion channels respond to electrical signals instead of ligands. Some receptor proteins are intracellular. Intracellular signal receptors are found in the cytosol or nucleus of target cells. To reach these receptors, a chemical messenger passes through the target cell’s plasma membrane. Such chemical messengers are either hydrophobic enough or small enough to cross the phospholipid interior of the plasma membrane. Hydrophobic messengers include the steroid and thyroid hormones of animals. Another chemical signaling molecule with an intracellular receptor is nitric oxide (NO), a gas whose small size allows it to pass between membrane phospholipids. Testosterone is secreted by the testis and travels through the blood to enter cells throughout the body....
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.

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