BIOLOGY 2D03 Lecture Notes - Protein Kinase A, Futile Cycle, Allosteric Regulation
28 Jan 2013
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Glycogen metabolism glycogen approx 1 day"s worth of stored energy liver highest concentration glycogen here serves as buffer rapidly depleted upon fasting. Glycogen degradation: glycogen phosphorylase phosphorylitic cleavage of glycogen results in glycogen and g1p requires plp pyridoxal phosphate. G6p can enter glycolysis be dephosphorylated and exported (liver only) enter pentose phosphate pathway. **reversible enzyme** (used in both glycognesis and lysis) Degradation regulation reciprocal regulation prevents futile cycle: glucagon/epinephrine binding receptors results in camp cascade, protein kinase a is activated, pka phos. Glypase further activated by calcium binding inc. available glucose upon muscle contraction. Atp, g6p deactivate glycogen breakdown inhibited activated form, however, is insensitive to allosterics. Glycogen synthesis: udp glucose pyrophosphorylase requires high energy reagent: udp glucose. Insulin triggers signal cascade phosphoprotein phosphatase act. also freed from glypase by glucose. Glycogen storage disease von gierke"s liver enlargement, hypoglycemia (glycogen accum. )
