11:115:301 Lecture Notes - Lecture 18: Pentose Phosphate Pathway, Glycogen Phosphorylase, Phosphorylase Kinase
22 Sep 2019
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Liver glycogen molecules are 10% of cell mass. Stored for local use of that muscle. Each step turns on or enables the next step. 7tm receptor beta adrenergic receptor g proteins adenylate cyclase camp protein kinase. Protein in center of glycogen = glycogenin. Non-reducing ends where glycogen will grow from. Protected by attachment to a tyrosine of glycogenin. Glucose is released from glycogen as g1p. Dephosphorylation + release into the bloodstream (liver) Glycogen --glycogen phosphorylase glucose 1-phosphate --phosphoglucomutase--> glucose 6-phosphate. Glucose 6-phosphatase glucose blood for use by other tissues. Fight or flight + starvation increase blood glucose levels. Glycogen phosphorylase (the first allosteric enzyme) liberates g1p from glycogen. Chain of >4 glucose molecules must enter + turn to find the catalytic phosphate. 4-8 glucose residues can be processively phosphorylase before it reaches an a1-6 linked. Exclude water to prevent hydrolysis of the glycogen. Need to bury catalytic site to prevent hydrolyzation waste atp site feed into it.
