glycogen phosphorylase regulation hut diagram

Question 1

phosphorylase A

Answer 1

phosphorylated form with serine 14 being +Pi.

Question 2

phosphorylase B

Answer 2

not phosphorylated at serine 14

Question 3

crossing the roof

Answer 3

need to use phoshorylase kinase, PhK, which is responsible for phosphorylating both serines. This +Pi can ONLY occur if in the T form of Phosphorylase B.

The dephosphorylation which is done by phospho protein phosphatase (PP1), can only occur if in T form of Phosphorylase A.

Question 4

Can only dephosphorylate in form

Answer 4

T state of A

Question 5

can only phosphorylate in form

Answer 5

T state of B

Question 6

allosteric effectors of left hand side

Answer 6

these are ATP and or G6P and AMP, the equilibrium favors T form caused by ATP/G6P.

On the right side, the R conformer is favored unless Glucose AND G6P is present.

Question 7

left hand wall

Answer 7

more important in muscle tissue

Question 8

right hand wall

Answer 8

more important in the liver tissue.

Question 9

AMP much less than ATP in cellular conditions

Answer 9

explains why T form is predominant form ( allosteric effector for R form of B is AMP)

Question 10

phosphorylase A + R

Answer 10

MOST active form

Question 11

no allosteric effectors on right side wall

Answer 11

the state of A + T is a placeholder state that is just ripped through to get to the A+R form unless there is a lot of glucose + G6P.