Glycogen synthesis and breakdown

~55,000 glucose → β-particle; 20-40 β-particle → α-rosettes

Structure of glycogen

oligo (α1→6) to (α1→4) glucatransferase

Glucosen Pi Glycogen phosphorilase

Liver Glucose-6 phosphatase

Glucose

Glucose 1-phosphate Phosphoglucomutase

Glucose 6-phosphate Pi

glycolysis Lactate

Piruvate

Lactate dehydrogenase

PDC CO2

Acetil-CoA TCA CO2 +H2O

Glucosen Pi Glycogen phosphorilase

Liver Glucose-6 phosphatase

Glucose

Glucose 1-phosphate Phosphoglucomutase

Glucose 6-phosphate Pi

glycolysis Lactate

Piruvate

Lactate dehydrogenase

PDC CO2

Acetil-CoA TCA CO2 +H2O

Synthesis of glycogen Muscle, liver: D-glucose + ATP → D-glucose-6-phosphate + ADP (hexokinase, glucokinase)

Erythrocyte, liver: D-glucose → lactate → D-glucose-6-phosphate glucose-6-phosphate ↔ glucose-1-phosphate (phosphoglucomutase) glucose-1-phosphate + UTP → UDP-glucose + PPi (UDP-glucose

pyrophosphorylase)

amylo (1→4) to (1→6) transglycosylase

Glycogenin Tyr-OH Self-glucosylating

8 UDP-glucose 8 UDP

Tyr-O-glucose8

Primered glycogenin Glycogen synthase and Branching enzyme Tyr-O-

n UDP-glucose n UDP

glucosen

α1,4 and α1,6 linkages

Glycogenin-glycogen complex

A Glc-6-P → glikogén átalakítás ára: glukóz-6-foszfát ↔ glukóz-1-foszfát (foszfoglukomutáz) glukóz-1-foszfát + UTP → UDP-glukóz + PPi (UDP-glukóz foszforiláz) PPi + H2O → 2Pi (inorganikus pirofoszfatáz) UDP-glukóz + glikogén (n) → glikogén (n+1) + UDP (glikogén szintáz) UDP + ATP → UTP + ADP (nukleozid difoszfát kináz) Összesítve: Glc-6-P + ATP + glikogén (n) + H2O → glikogén (n+1) + ADP + 2Pi