4

Regulacja syntezy i degradacji glikogenu

Ser¹⁴ OH side |

(Glucose)„ + Pj-► (glucose)*-! + glucose 1-phosphate

OH Ser¹⁴ side

CH., chain

/ *

Glycogen

Shoi*tened

glycogen

chain

Phosphorylase a + 2H₂0-► phosphorylase b + 2Pi ^P pKo«phatase

(morę active)

(less active)

(PPD

-1-

Phosphorylase b (less active)

2Pj 2ATP

2H₂0 2ADP

mięśnie stan spoczynku

<er

glucagon

^'(liver)

A

/

phosphorylase b kinase

®L cpincphrinc.

"'•tlCa²’|,tlAMPl (muacle)

2ATP + phosphorylase b (less active)

2ADP + phosphorylase a (morę active)

-7—

Phosphorylase a (active)

_L_

ch₂

©

o

FIGURĘ 15-24 Regulation of muscle glycogen phosphorylase by covalent modification. In the morę active form of the enzyme, phosphorylase a, Ser¹⁴ residues, one on each subunit, are phosphorylated. Phosphorylase a is converted lo the less active form, phosphorylase b, by enzymatic loss of these phosphoryl groups, catalyzed by phosphorylase a phosphatase (PP1). Phosphorylase b can be reconverted (reactivated) to phosphorylase a by the action of phosphorylase b kinase.