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Dr. Bechhofer's Fun House 5
Signal Transduction and the Regulation of Transcription
14
Biochemistry
Graduate
09/24/2010

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Term
what happens when glucose is abundant? When it is lacking?
Definition
When abundant: glycolysis, when not: gluconeogenesis.
Term
When you have low blood glucose and need fast response, what happens?
Definition
PFK2 is phosphorylated and pyruvate kinase gets phosphorylated so it gets all horny and goes after shit so it can catalyze key steps in glycolysis and gluconeogenesis. This has to do with glucagon and the Gs pathway.
Term
What does the PEP carboxy kinase (PEPCK) gene do?
Definition
Its product is the rate-limiting step of gluconeogenesis. Long term activity of the gluconeogenesis pathway is controlled by the transcription levels of the PEPCK gene.
Term
what are the three ways that a 5' cap does shit?
Definition
1. It protects from exonucleases by making a 5' to 5' bond, so that the exonuclease can't attack an open 5'. 2. helps with export to the nucleus. 3) helps with getting into the ribosome
Term
How is the polyA tail useful?
Definition
Term
Besides a higher melting point, why does transcription differ in regions where there is alot of C-G binding?
Definition
This has to do with CpG islands and methylation. A good example of this is L1 retrotransposons in eukaryotes: which are heavily methylated to discourage RT.
Term
what happens when there is chronically low glucose?
Definition
Glucocorticoids are produced by the adrenal cortex which causes long-term upregulation of the PEPCK gene.
Term
What happens to PEPCK when there is high glucose and what causes this?
Definition
PEPCK transcription is inhibited by high glucose levels because of insulin.
Term
What does PFK2 do in low blood glucose?
Definition
Glucagon binds at GPCR. Adenylyl cyclase is activated. cAMP is increased which activates PKA. PKA phosphorylates PFK2, INACTIVATING IT-->then gluconeogensis happens.
Term
what does Pyruvate kinase do with low glucose?
Definition
Glucagon binds at GPCR. Adenylyl cyclase is activated. Increase cAMP, causing elevation of PKA. PKA phosphorylates glycolysis enzyme pyruvate kinase--TURNING ITOFF. This stops glycolysis and STARTS GLUCONEOGENESIS.
Term
what are some positive regulators of PEPCK expression?
Definition
So like after glucagon binds, shit goes DOWNNNNNN. GPCR gets bound, adenylyl cyclase is secondarily activated which increase levels of cAMP which activates PKA. yeah baby. The catalytic subunit of PKA dissociates and goes to the nucleus where if phosphorylates CRE-Binding Protein (CREB). CREB then binds to the DNA enhancer sequence CRE (cAMP response element). It also interacts with CBP/300 which makes CREB stimulate TXN babyyyyyy
Term
Where does glucocorticoid do?
Definition
It binds to glucocorticoid receptor protein, which is in the cytoplasm. This exposes the NLS and the GR-GC complex goes to the nuclus and functions as a transcription factor. THIS BINDS TO THE RESPONSE ELEMENT on the DNA. Transcription of PEPCK gets activated.
Term
What does insulin do for PEPCK?
Definition
insulin acts through a receptor tyrosine kinase (RTK) to inhibit gluconeogenesis and increase glycogen storage. basically, as a result of insulin binding the RTK, a REPRESSSOR bINdS TO thE INSULIN RESPONSE ELEMENT, which represses transcription of PEPCK. this is a strong ass effect, beotch.
Term
in what kind of cells are PEPCK expressed? if it isn't expressed in a certain type of cell, what causes it to not be expressed?
Definition
Hypermethylation causes it to not be expressed in ALL CELLS besides THE LIVER.
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