Insulin Flashcards
Insulin key proteins
1) Glut4
2) Protein Kinase B (PKB)
3) Protein Phosphatase 1 (PP1)
4) Glycogen Synthatase Kinase 3 (GSK3)
Signaling cascade involving insulin
Insulin-receptor, activating PKB
GLUT translocates to membrane
PKB activates PP1
PKB inactivates GSK1
PP1 activates Glycogen synthase
PP1 inactivates glycogen phosphorylase
PKB
activates PP!, inactivates GSK3
PP1
activates Glycogen synthase
inactivates glycogen phosphorylase
What does a mutated insulin receptor cause
causes PP1 to inactivate glycogen phosphorylase and inactivate pyruvate kinase: glycogen is not released from liver
high blood glucose leads to
high insulin, stimulates glycogen synthase
insulin to receptor–> activation of PKB –> GLUT translocation, PPI activation/GSK3 inactivation
PPI activates glycogen synthase
low blood glucose leads to
high glucagon, stimulates gluconeogenesis and glycogenolysis
glucagon is released from ___ cells: what enzymatic cascade occurs
- alpha cells
glucagon binds to GCMP–>adenylate cyclase –> cAMP
cAMP activates Protein kinase A
PKA inactivates Glycogen synthase Oka inhbits PP1
PKA phosphorylates activate
PK activates glycogen phosphorylase
pathway defective in type II diabetes
glucagon’s ultimate outcome i
inactivation of glycogen synthetase and activation of glycogen phosphorylase
glucagon enzyme cascade sequence
glucagon–> GPCR –> adenylate cyclase–> cAMP –> PKA–>inactivation of PPI and glycogen synthase, activates PK which activates glycogen phosphorylase
other regulatory mechanisms of glycogen break down/synthesis
epinephrine: fight or flight response
breakdown of glycogen
PW similar to glucagon
allosteric inhibitors
Glucose 6 phosphate - activates glycogen synthase, inactivates glycogen phosphorylase
glucose 6 phosphate
allosterically stimulates glycogen synthase
inactivates glycogen phosphorylase
free glucose
allosteric inhibitor of glycogen phosphorylase in liver but not muscle
