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19 Cards in this Set
- Front
- Back
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What are some factors that determine the activity of proteins/enzymes?
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Association with regulatory proteins, sequestration (ie. compartmentation), and covalent modification.
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What are enzymes that promote dephosphorylation called?
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Phosphotases.
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What are enzymes that promote phosphorylation called?
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Kinases.
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What effects can phosphorylation have on an enzyme?
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It can alter its activity, control location within the cell, provide specific docking sites for other proteins, and control degradation of the enzyme.
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What two amino acids residues are most commonly phosphorylated?
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Ser (86%) and Thr (12%).
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Summarize the pathway that makes adrenaline cause an increase in glucose levels. Also describe the regulatory mechanisms.
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Adrenaline binds to the receptor, which causes GTP to replace GDP in some molecule, which then moves to adenylyl cyclase and activates it. Adenylyl cyclase then catalyzes the conversion of ATP to cAMP, which activates PKA. PKA phosphorylates a whole lot of different things, the sum effect of which is to signal the breakdown of glucose. The system is regulated by phophotases, and by 5'-AMP, the degraded form of cAMP.
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Describe a "receptor enzyme" signal transduction system.
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The ligand binds extracellularly, causing an increase in intercellular activity.
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Describe a "gated ion channel" signal transduction system.
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Gate opens or closes due to binding of ligand or membrane potential.
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Describe a "serpentine receptor" signal transduction system.
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Extracellular ligand binds to receptor, activating an intracellular GTP-binding protein, which regulates an enzyme that generates an intracellular second messenger.
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Describe a "steroid receptor" signal transduction system.
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A steroid binds to a nuclear receptor protein, which can then regulate certain genes.
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Describe a "receptor with no intrinstic enzyme activity" signal transduction system.
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Receptor interacts with cytosolic protein kinase, which activates a gene-regulating protein (sometimes indirectly).
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Describe an "adhesion receptor" signal transduction system.
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Binds molecules in extracellular matrix, changing conformation and altering interactions with cytoskeleton.
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What is PP-1? What is its usual mechanism? How does it regulate all of the different reactions that it is involved in?
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It is protein phosphotase-1. It is a dephosphorylator. It has about 200 sub-units to regulate all of the processes it is involved in.
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What are the main ligands and receptors in neurons?
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Neurotransmitters and their receptors.
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What is DARPP-32? What is its homologue?
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It is the "master switch" for phosphorylation of many protein targets, most notably PP-1. Its homologue is I-1.
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Which is the activated state of DARPP-32, phosphorylated or dephosphorylated? What enzyme activates it?
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The active state is phosphorylated. PKA (with the input of ATP) activates it.
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How does Nodularin affect PP-1? What effects does this have on the body?
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It blocks PP-1. This alters many cell functions, and can significantly alter tumor supression and kidney dialysis, and cause liver cancer and necrosis.
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How are microcystins and Nodularin related?
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They have similar structures and the same hepatotoxic effect.
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Why might microcystin-infected stuff be marketed as a "vitality-increasing drug"?
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It does upregulate the adrenaline pathway.
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