Glycogen Metabolism

Question 1

Glucose -6-P- ——> G1P

Answer 1

Phosphoglucomutase

Question 2

G1P —–> UDP Glucose

Answer 2

Glucose 1-Phosphate uridyly transferase

Question 3

Glucose to Glycogen

Answer 3

Glycogen synthase

Question 4

Glycogen to glucose

Answer 4

Glycogen phosphorylase

Question 5

Glycogen synthase makes what?

Answer 5

the alpha 1,4 linkages not the 1,6 linkages

Branching enzyme makes the 1,6 linkages

Question 6

Breaks the alpha 1,4 linkages?

Answer 6

glycogen phosphorylase

requires bit B6

Question 7

Basic relationship of blood glucose and PKA

Answer 7

high blood glucose = low PKA (don’t want to Phosphorylase the Glycogen synthase)

low glucose = high PKA (want to inhibit glycogen synthase )

Question 8

Glucagon , epi activate—? while Insulin Activates?

Answer 8

Glucagon and epi activates PKA which inhibits activity go Glycogen synthase so that no more glycogen will begin to stored, cause instead it need to be broken down.

Insulin means that there in high blood glucose and therefore it will activate PP1. PP1 will dephosphoryate glycogen synthase therefore making glycogen storage and synthesis more favorable.

Question 9

Regulation of PP1

Answer 9

PP1 is regulated by inhibitor 1.

-Only when inhibitor 1 is phosphorylated can it inhibit PP1. What phosphorylates inhibitor 1? Easy.. PKA..

The logic flows likes this….. When glucose levels are high ,that means glycogen synthase needs to working. This can only be done when it is dephosphorylalted by PPI. So, at this point, PKA levels are low because glycogen synthase does not need to be inhibited by phosphorylation. Thus since PKA levels are low,, then it will not phosphorylate inhibitor 1 so, inhibitor 1 cannot block the PP1.

Opposite scenario …

Low blood glucose levels … we need to now turn off glycogen synthase. We don’t have the glucose to store!! This means that PKA levels will increase to inhibit glycogen synthase. When PKA increases , it phosphorylates inhibitor 1 which is turn blocks the activity of PP1 so that PP1 cannot dephosphorylate the glycogen synthase enzyme.

Question 10

Some noted activates of Glycogen synthase

Answer 10

G6P

PP1

and PKA in an inhibitor

Question 11

Inhibitors and activators of glycogen phosphorylase

Answer 11

I:
ATP.GTP

A: AMP

Question 12

What phosphorylates glycogen phosphorylase ?

Answer 12

Phosphorylase kinase !!

PP1 will dephosphoryate the glycogen phosphorylase and will store more glycogen. This makes total sense because glycogen phosphorylase is deactivated with PPi , but glycogen synthase is activated with PPI.

Question 13

What phosphorylates the phosphorylase kinase ?

Answer 13

PKA will phosphorylate the phosphorylase kinase then it will phosphorylate the glycogen phosphorylase

Make it make sense … PKA will inhibit glycogen synthase , but it activates phosphorylase kinase which phosphorylates and activates glycogen phosphorylase.