BE230_Lecture_21 - Cell Structure & Function BE230 Dr...

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Cell Structure & Function BE230 Dr Christine Loscher Lecture 10
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For next day What processes use cAMP? What processes use Calcium? Target tissue, signaling molecule and cell response
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Target tissue/cell Signaling molecule/ligand Second messenger Cell response Muscle cells Acetylcholine Ca Muscle cell contract BM cells cAMP Prolif/diff Kidney Ca Mineral excretion
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G protein linked receptors G proteins and ion channels G protein linked receptor desensitization Diseases that affect G proteins G protein defects that lead to disease
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G proteins can activate ion channels In some cases G proteins directly activate or inactivate ion channels in the plasma membrane of the target cell, thereby altering the ion permeability and hence the excitability of the membrane Example: Acetylcholine reduces both the rate and strength of heart muscle cell contraction - A special class of acetylcholine receptors that activate the G i protein mediates this effect. Once activated, the α subunit of G i inhibits adenylyl cyclase, while the β γ complex binds to K + channels in the heart muscle cell plasma membrane to open them. The opening of these K + channels makes it harder to depolarize the cell, which contributes to the inhibitory effect of acetylcholine on the heart.
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G proteins can activate ion channels Other trimeric G proteins regulate the activity of
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This note was uploaded on 01/05/2010 for the course FSH BT taught by Professor Ianmarison during the Fall '09 term at Dublin City University.

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BE230_Lecture_21 - Cell Structure & Function BE230 Dr...

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