pharmacology questions

pharmacology questions - Pharmacology questions The role of...

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Pharmacology questions The role of protein phosphorylation in cell signalling The major mechanism that controls cell signalling from of information from the receptor surface to the gene is protein phosphorylation. Phosphates are transferred from ATP to be esterified with certain amino acid residues. This modifies protein structure and its interactions. This could have any number of actions, for instance, determining the location of an enzyme, controlling gene expression, regulating cell to cell interactions and signalling its destruction or preventing this. Kinazses are involved in this pathway. Receptor kinases o Will generate an input signal. o There will be slow activation of ligand and thus slow response. o Receptors will be phosphorylated and phosphorylation cascade intitiated so cytosolic kinases become involved to amplify and spread the signal. Cytosolic kinases o Cells can choose between several phosphorylation cascades. o There are kinases in these cells with responses to second messengers such as PKA, PKC and calcium-calmodulin dependent kinases. o There are separate casacades for each. Protein kinases have a regulatory subunit (R), catalytic subunit (C) and a pseudo substrate domain (P). An activator which binds to R will cause P to dissociate from C and thus catalytic activity occurs. PKA: o When activated by cAMP there is dissociation of R and C subunits. o The C subunit is phosphorylated and activated. o Cardiac channels thereby increase cardiac force. o Parietal cell proton pump will increase gastric acid secretion. o Adipose hormone sensitive lipase will increase fat mobilization. o PDE4 will increase cAMP degradation. The G protein Ras controls signalling through the MAP kinase cascade. There is reversal of phosphorylation by phosphatises. Thereby signals are fine tuned by downregulation of amplitude.
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Muscle contraction and neuronal function is dependent on ion channel function. How
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pharmacology questions - Pharmacology questions The role of...

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