12. Fructose 1,6-bisphosphatase (fbp) is a highly requlated enzyme required for
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12. Fructose 1,6-bisphosphatase (fbp) is a highly requlated enzyme required for gluconeogenesis. Fbp transcription is stimulated by CAP (called CP in biocyc- they are the same protein) when it is bound to CAMP. Therefore, fop will be more highly expressed when cAMP levels are high. Under what conditions do CAMP levels rise? Explain why you think it would help the cell to have fop expression depend on cAMP levels? Go to: "Pathway: TCA cycle 1 (prokaryotic)" 13. In the TCA cycle, a 4-carbon molecule, oxaloacetate, is converted into a 6-carbon molecule by the addition of an acetate group. Which enzyme adds the extra 2 carbons in the form of an acetate? reconstituted. In the process, several molecules are reduced by addition of hydrogens and electrons. These reducing equivalents are important for respiration. What four molecules can be reduced? 14. In the TCA cycle, the two carbons from the acetyl CoA eventually get released as CO2, and oxaloacetate isExplanation / Answer
Ans. 12. The conditions in which cAMP levels will rise are:
Cyclic AMP is formed from ATP by action of enzyme adenylyl cyclase. Its level can increase by stimulating the enzyme adenylyl cyclase and GTP is required for the hormonal stimulation of adenylyl cyclase. G protein coupled receptors are required for the adenylyl cyclase activation.
Glucose level also cause change in the level of cAMP because the glucose rich and glucose limited states alters the transport flux through the phosphoenol pyruvate - glucose phosphotransferase system(PTS) which in turn controls the adenylyl cyclase activity.
It helps the cell to have fructose 1,6 bisphosphotase expression depend on cAMP levels because cAMP is very useful, it acts as a second messenger important in many biological processes and also used for intracellular signal transduction. Protein kinase A activity is also depend on cAMP and protein kinase in turn helps in the activation of glycogen phosphorylase which convert glycogen to glucose - 1-phosphate and deactivates the glycogen synthase. The enzyme fructose -1,6 bisphosphotase also favour the formation of glucose and cAMP is doing the same work for it.
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