human phys lec 6 - Metabotropic Gproteins GPCRs...

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Metabotropic receptors for neurotransmitters are coupled to heterotrimeric G proteins ese receptors are a member of a very large family of proteins called These receptors are a member of a very large family of proteins called GPCRs GPCRs have seven membrane spanning alpha helices The activated receptors cause activation of adjacent membrane proteins called G proteins. 1 2 3 NH 2 4 5 6 7 COOH
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GPCR at rest in association with a G protein eceptor NT Receptor G protein G protein α‐ and γ subunits are associated with plasma membrane by lipid anchors
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PCRs and activation of G roteins GPCRs and activation of G proteins NT NT Neurotransmitter binding causes activation of the G protein. The α subunit and the βγ dimer can independently activate other systems
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Regulation of the activity of heterotrimeric G proteins: the GTPase cycle GDP GTP GPCRs active ctive Inactive GTPase GDP Active GTPase GTP RGS proteins P i
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eterotrimeric roteins have and bunits Heterotrimeric G proteins have α , β , and γ subunits Inactive resting form Active form (GTP attached) Inactive form (GDP attached)
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General features of transduction through GPCRs Cascade effect –the signal gets mplified each ep amplified at each step. Pleiotropic – multiple processes regulated by a single signal Cross talk – components are shared with other transduction events going n in the same cell on in the same cell. Pleiotropic: 1. Producing many effects definition Greek plei ō n meaning ‘multiple, or excessive’ Greek tropo, meaning ‘to respond’
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Adenylate cyclase and cAMP: A very well studied second messenger pathway 1. Neurotransmitter binds to GPCR, which activates a G protein . he G rotein activates denylate Adenylate cyclase Neurotransmitter 2. The G protein activates adenylate cyclase (AC) 3. AC converts ATP to cAMP Protein kinase A 4. cAMP binds to and activates protein kinase A (PKA) 5. PKA phosphorylates target proteins (using ATP as a substrate), thereby changing their activity
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roduction of 3’ clic AMP by denylate clase Production of 3 5 cyclic AMP by adenylate cyclase Adenylate cyclase 5’ + PP 3’ ATP cAMP related enzyme, uanylate clase n form MP which A related enzyme, guanylate cyclase can form cGMP, which is also a second messenger
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This note was uploaded on 01/26/2012 for the course BIOL 3324 taught by Professor Ziburkus during the Spring '07 term at University of Houston.

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human phys lec 6 - Metabotropic Gproteins GPCRs...

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