BIBC 120 Lecture 15: Week 6.1
Week 6.1
REGULATION OF BLOOD GLUCOSE
- Glucose enters cells: Dietary glucose is taken up in cells in your body by GLUT
transporters (facilitated diffusion)
o GLUT 1
o GLUT 3
o both basal uptake, low Km, high affinity
o GLUT 4 insulin responsive
- glucose (phosphorylated) → glucose 6P (gluconeo)----(glycolysis)→ pyruvate (PDH
complex)→ acetyl CoA → Citric Acid Cycle → oxphos
o glucose can be converted to glycogen (liver and muscle)
o AcCoA can be converted to fatty acids (liver and adipose tissue), FA → acCoA
o cannot convert FA back to carbohydrates
fasting blood glucose 5mM (glucose not taken up by pancreas effectively
Regulate carbohydrate metabolism and blood glucose concentration
1) insulin: pancreas b cells, secrete in response to inc BG
2) glucagon: pancreas a cells, secrete in response to dec BG
INSULIN
- Insulin Release
o GLUT 2 (high km) transports glucose in
o glucokinase phosphorylates glucose
o glycolysis/oxphos to make ATP
o ATP closes K channel, membrane depolarization, opens Ca2+ channel
o Exocytosis of insulin vesicles, insulin release
- Insulin is a protein hormone (51 amino acids)
- The insulin receptor is a trans-membrane protein with an intrinsic tyrosine kinase
activity
- Insulin binding causes receptor dimerization, activation of the tyrosine kinase activity,
and intracellular signal transduction
- Insulin receptors are found on insulin-responsive tissues: muscle (skeletal and cardiac),
adipose (fat), and liver.
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Document Summary
Glucose enters cells: dietary glucose is taken up in cells in your body by glut transporters (facilitated diffusion: glut 1, glut 3, both basal uptake, low km, high affinity, glut 4 insulin responsive. Regulate carbohydrate metabolism and blood glucose concentration: insulin: pancreas b cells, secrete in response to inc bg, glucagon: pancreas a cells, secrete in response to dec bg. Insulin release: glut 2 (high km) transports glucose in, glucokinase phosphorylates glucose, glycolysis/oxphos to make atp, atp closes k channel, membrane depolarization, opens ca2+ channel, exocytosis of insulin vesicles, insulin release. Insulin is a protein hormone (51 amino acids) The insulin receptor is a trans-membrane protein with an intrinsic tyrosine kinase activity. Insulin binding causes receptor dimerization, activation of the tyrosine kinase activity, and intracellular signal transduction.