LEC C Flashcards
How is glycogen synthase in the liver regulated when glucose levels are low?
There are 9 sights of phosphorylation on glycogen synthase that will make glycogen synthase inactive. These 9 sights can be phosphorylated by 11 different enzymes!
p.s. The more phosphorylated the enzyme is the more inhibited it is.
True or False: PKA will also phosphorylate glycogen synthase in the liver when glucagon is elevate and inhibite the ezyme.
True PKA does a lot of things. And one of the things PKA does is inhibit gylcogen synthase by phosphorylating one of the 9 sites of phosphorylation.
What are all the things that PKA does in the Liver when blood glucose is low?
When glucose in the blood begins to rise which of the following needs to happen in the liver?
A) Phosphorylate glycogen synthase, glycogen phosphorylase kinase, glycogen phosphorlyase.
B) Phosphorylate PFK2/FBPase2
C) Dephosphorylate glycogen synthase, glycogen phosphorylase kinase, glycogen phosphorlase
D) A and B
F) C and D
C
GLUT 4 be placed into the membrane of the muscle? Yes, this way glucose can be uptaken by the cell to generate ATP. Question #2) Upon neuronal signaling in skeletal muscle, what is released into the cytoplasm from the sarcoplasmic reticulum? Calcium I believe? Question #3) T2DM is a condition that can result in high blood glucose due to ineffective insulin signaling in the muscle cell. What is a possible drug target for this disease in skeletal muscle? AMPK by activating the gluc 4 containing vesicles to fuse with the membrane.
PKA overall is a signal saying what about blood glucose levels?
That blood glucose levels are low.
What happens in the liver when blood glucose is high?
F26BP is an activator of what?
PFK1. PFK1 converts F6P to F16P when glucose is high.
How is the bifunctional enzyme affected by high glucose levels in the liver?
Insulin DEphosphorylates phospho-protein phosphatase which then DEphosphorylates the bifunctional enzyme so that the PFK2 domain can make F26B from F6P. And F26BP will activate PFK1 increasing flux through glycolysis.
What happens to PP1c when glucose goes up in the liver?
What happens to glycogen phosphorylase when glucose levels go up in the liver?
Glucose or G6P will bind to it in an allosteric site causing a confimational change popping the phosphorylases out. PP1c will then cleave off the phosphates. This wil then make phosphorylase less active (phosphorylase b).
What does PP1c do in the liver when their is high glucose?
PP1c DEphosphorylase glycogen synthase, DEphosphorylase phosphorylase kinase. This will activate glycogen synthase and inhibite phosphorylase kinase.
Review of High blood glucose in the liver
See sound recording.
Glyburide and Glipizide are effective drugs in treatment of T2DM. If I told you that the target of their action is the SUR1 protein, what do you think would be their mechanism of action? inhibiting or activating?
INHIBITS! ATP generated in glycolysis actually inhibits the k-channel and this stop K+ from leaking out of the cells and this CAUSES a DEPOLERIZATION of the cell membrane which opens calcium channels which then calcium will activate the release of insulin.
