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50 Cards in this Set
- Front
- Back
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How do cells communicate |
Hormones Neurotransmitter/ lipid mediators/ peptide |
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Where are receptors mostly located |
External plasma membrane |
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What are the exceptions for receptors mostly being in the external plasma membrane |
Nuclear receptors |
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What function does an active Intracellular signalling cascade result in |
Cell movement Muscle contraction Cell growth |
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What are the types of receptors |
Ligand hated ion channels GPCRs Kinase linked receptors Nuclear receptors |
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What drugs are used for GPCRs |
Mostly antagonists and inverse agonists |
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What inhibitors are not used clinically |
PKA and PKC |
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What is a synthetic peptide |
7-20 amino acid fragment of GPCR Intracellular loop nature engineered specificity, interacts with its cognate receptor |
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What is hydrophobic moiety |
Cell penetrating/ membrane tethering lipid |
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What is the generalised pathway of a ligand gated ion channel once a ligand has bound to it |
Ligand binds to ion channel receptor Receptor opens the ion channel This causes a depolarisation to cause excitation or inhibition In milliseconds |
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What are examples of ligand gated ion channels |
Nicotinic Ach receptor |
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What is the protein phosphorylation pathway of a GPCR |
Ligand binds to receptor forming second messaged cAMP cAMP promotes activation of PKA leading to protein phosphorylation The phosphorylation happens to proteins on serine and threonine The phosphorylation leads to either activation or inactivation This happens as PKA is splits ATP and transfers terminal phosphate to covalently modified proteins This represents a molecular which which can turn the cells response on or off of effect |
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What is the GPCR pathway that involved Ca2+ release |
ligand binds to receptor receptor activates G-protein Gq coupling to PLC, PLC cleave PIP2 to produce two secind messangers IP3 and DAG IP3 binds to an Intracellular receptors to promote the release of calcium into the cytoplasm from the ER. The calcium then goes on to activate calcium dependent cellular processes such as mitosis and cell growth |
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What is the pathway of a kinase linked receptor |
Ligand binds to receptor and activates kinase that is part of the receptor. The kinases phosphorylate proteins on tyrosine residues to activate them This creates a signalling cascade that results in the activation of transcription factors that turn on genes The protein products that regulate processes such as mitosis and cell growth |
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Why does GDP slowly disassociate from G protein |
Milli molar concentration of magnesium are present |
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What is the typical time scale of GPCR |
Seconds |
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What is the pathway of a nuclear receptor |
Ligand binds to receptor promoting formation of a complex that moves to the nucleus The complex functions as a transcription factor to turn on or off genes The protein products regulate processes such as cell growth and differentiation |
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What happens when the GPCR is free from GDP |
GTP will bind and this reaction occurs faster then GDP are binding |
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What are the four major classes of GPCR |
Rhodopsin family Secretion family Metabotrophic family Pheromones, taste and odorant receptors |
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Where does GTP bind to |
Alpha subunit |
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What is the secretion family |
Receptors fit peptide hormones eg. Glucagon Intermediate extracellular tail incorporating ligand binding domain |
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What happens after GTP has bound to alpha subunit |
Dissociation of the alpha beta gamma G proteins occurs |
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What does activates GTP bound alpha subunit interact with |
Adenylyl cyclase and stimulates cAMP synthesis |
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What are beta adrenoceptors, H2 histamine, PG12 and PGE2-receptors All linked the activation of |
Adenyly cyclase which promotes cAMP formation and PKA activation as well as the opening kg Ca2+ channels via Gs |
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What does the agonist receptor complex increase the rate of GDP in GPCR |
Release of GDP |
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How is increased rate of GDP achieved |
The agonist receptor complex lowering the concentration requirement for the magnesium dependent GDP release |
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What happens when the GPCR is free from GDP |
GTP will bind and this reaction occurs faster then when GDP are binding |
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What does the binding of Gs lead to |
Increase in adenylyl cyclase and Ca2+ channel |
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What does the binding of Gi lead to |
Decrease in adenylyl cyclase Increase in K+ channel |
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What does the binding of Go lead to |
Ca2+ channel decrease |
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What does activated GTP that is bound to an alpha subunit interact with |
Adenylyl cyclase and stimulates cAMP synthesis |
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What do beta adrenoceptors, H2 histamine, PG12 and PGE2-receptors All link to the activation of …. Via which G protein |
Adenyly cyclase which promotes cAMP formation and PKA activation as well as the opening of Ca2+ channels via Gs |
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What does the binding of G13 lead to |
Na+/H+ exchange |
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What can alpha 1 adrenoceptors and M3 muscarinic receptors activate |
PLC (InsP3 mobilises Intracellular Ca2+ inside the cell and DAG which activates PKC) via Gq |
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What is the adenylyl cyclase pathway to reduce glycogen synthesis |
Adenylyl cyclase system produces cAMP activating PKA in the liver PKA catalysed the phosphorylation of glycogen synthase It does this by converting if from an active form to an inactive form Switching off glycogen sythesis |
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What is the adenylyl cyclase pathway to increase glycogen breakdown |
Adenyly cyclase produces cAMP which activates PKA PKA phosphorylates phosphorylase A and activates it This enzyme causes glycogen to break down to glucose 1-phosphate |
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How can a hormone such as glucagon activate adenylyl cyclase |
Via a Gs coupled receptor to turn off anabolic processes like glycogen synthesis and then on catabolic processes such as glycogen breakdown |
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What is the adenylyl cyclase pathway to inverse lipolysis |
Adrenaline binds to beta 3 adrenoceptor in adipocytes causing activation of Adenyly cyclase producing cAMP cAMP activates PKA which activates triglyceride lipase to promote the breakdown of triglycerides This produces fatty acid wa that undergo oxidation to produce energy (ATP) |
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What is the GPCR pathway that involved Ca2+ release |
ligand binds to receptor, the receptor promotes the coupling G-protein Gq to PLC PLC cleave PIP2 to produce two secind messangers IP3 and DAG ip3 binds to an Intracellular receptors to promote the release of calcium into the cytoplasm from the ER. The calcium then goes on to activate calcium dependent cellular processes such as mitosis and cell growth |
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What is the pathway of a kinase linked receptor |
Ligand binds to receptor and activates kinase that is part of the receptor. The kinases phosphorylate proteins on tyrosine residues to activate them This creates a signalling cascade that results in the activation of transcription factors that turn in genes The protein products that regulate processes such as mitosis and cell growth |
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What inactivates PKA |
The regulatory subunit |
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What is the typical time scare of GPCR |
Seconds |
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What is the pathway of a nuclear receptor |
Ligand binds to receptor promoting formation of a complex that moves to the nucleus The complex functions as a transcription factor to turn in it off genes The protein products regulate processes such as cell growth and differentiation |
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How can a hormone such as glucagon activate adenylyl cyclase |
Via a Gs coupled receptor to turn off anabolic processes like glycogen synthesis and then turn on catabolic processes such as glycogen breakdown |
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What is the adenylyl cyclase pathway to increase lipolysis |
Adrenaline binds to beta 3 adrenoceptor in adipocytes causing activation of Adenyly cyclase producing cAMP cAMP activates PKA which activates triglyceride lipase to promote the breakdown of triglycerides This produces fatty acid that undergo oxidation to produce energy (ATP) |
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What is a pepducin |
Class of cell that penetrated the lipidated peptides |
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How can stimulation of GPCRs activate ERK |
Downstream of Gq pathway due to PKC |
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What are GPKs involved in |
Involved in GPCR desensitisation and internalisation |
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What is beta arrestin the scaffolding of |
Can bind to things to start a conformational change that allows something to be active on the C terminus |
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Does beta arrestin help to retain a signal |
Yes, if removed reduces longevity |
