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S 2007 BIOC 3406

S 2007 BIOC 3406. 02-08-07. Regulation. ~4000 genes (out of 35000 total) code for regulatory proteins (How many do you think encode hair or skin color?) Time scale of response to stress must range from msec to days or longer. Cell must respond to changes in levels of key intermediates.

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S 2007 BIOC 3406

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  1. S 2007 BIOC 3406 02-08-07

  2. Regulation • ~4000 genes (out of 35000 total) code for regulatory proteins • (How many do you think encode hair or skin color?) • Time scale of response to stress must range from msec to days or longer

  3. Cell must respond to changes in levels of key intermediates • ATP involved in many reactions • Demand can increase 100 fold in a few seconds • AMP (AMP dependent protein kinase, AMPK) • Ratios with ADP, AMP also important • NADH/NAD+ ratio also important • Metabolic intermediates • 3-phosphoglycerate (synthesis of serine) • DHAP (synthesis of fats)

  4. Regulation • Works to prevent “futile cycling” • Works to partition metabolites appropriately into different paths • Works to choose fuel (glucose, f.a.’s, etc.) • Works to shut down pathways if products accumulate

  5. Modification of Enzyme activity • Actual level of enzyme • Amount of transcription of the code • Rate of removal from service • Rate of activation (proenzymes) • Time scale minutes to hours • Covalent Modification • Phosphorylation/dephosphorylation • Adenylylation, methylation, attachment of lipids, attachment of sugars • Time scale seconds to minutes • Usually triggered by hormonal (nonlocal) signals

  6. Modification of Enzyme activity • Allosteric regulation • Inhibitor or promoter • Substrate or product, coenzyme, or product down the path • Local • Fast (msec to sec) • Compartmentalization (recall G 6-phosphatase catalyzed hydrolysis of G 6-P for blood glucose occurring in ER)

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