Glycolysis

hexokinase

turns glucose --> glucose 1 phosphate

exists in most tissue

stimulated by insulin

inhibited by glucagon and glucose 6 phosphate

Glucokinase

turns glucose --> glucose 1 phosphate

exists in liver and pancreatic cells

stimulated by insulin (glucose)

inhibited by glucagon and fructose 6 phosphate

PFK-1 reaction

turns fructose 6 phosphate ---> fructose 6 bisphosphate

PFK-1 activators

AMP

insulin

F-1,6 bisphosphate

want to keep glycoloysis on

PFK2

made during high insulin:glucagon ratio

makes F-2,6 phosphate

removal

(addition or removal) of a P group activates PFK2

PFK-1 inhibitors

citrate

ATP

glucagon

want to turn glycolysis off

PEP kinase activators

F-1,6 bisphospate

insulin

PEP kinase inhibitors

ATP

glucagon

PEP to pyruvate

last substrate level phosphorylation reaction

1,3 bisphosphate to 3 phosphoglycerate

first substrate level phosphorylation reaction

aldolase b

cleaves fructose 1 phosphate into glyceraldehyde and DHAP

HFI/Hereditary Fructose Intolerance

Causes accumulation of fructose 1 phosphate ( a toxin)

causes a build up of pyruvate from gluconeogensis

depletes phosphate stores for ATP synthesis

creates AMP --> makes urea

HFI symptoms

autosomal recessive

1)hypoglycemia, 2)uricemia 3)lactic acidemia

jaundice, cirrhosis, vomiting,

causes liver cell damage

fructokinase

phosphorylates fructose or sucrose, making fructose 1 phosphate

Glyceraldehyde-3-phosphate to 1,3 bisphosphoglycerate

arsenic inhibits this reaction

one step before first substrate level phosphorylation reaction

Essential fructosuria

Fructokinase deficiency

asymptomatic

GLUT 1

transporter in red blood cells (RBCs) and blood-brain barrier

GLUT 2

bidirectional transporter in liver, kidney, and pancreas

GLUT 3

transport in neurons

GLUT 4

insulin dependent

specific transport for muscle and adipose tissue

GLUT 1 deficiency syndrome

results in intractable seizures in infancy and developmental delay

GLUT 5

small intestine and the testes

fructose transporter