1: Other Metabolic Sugars & PPP Flashcards
GLUT5 function
Fructose uptake
Polyol pathway purpose
Converts glucose into fructose
Two steps and the enzymes in the polyol pathway
- Glucose -> sorbitol by aldolase reductase
2. Sorbitol -> oxidized to fructose by sorbitol dehydrogenase
Why are the kidney, retina, and Schwann cells relevant in the polyol pathway?
They lack sorbitol dehydrogenase - accumulate sorbitol, causing water influx and swelling
What can sorbitol accumulation caus?
Cataracts, retinopathy
What happened when fructose enters glycolysis?
It bypasses the rate limiting steps -> is processed unregulated
What happens with excess fructose consumption?
Excess acetyl CoA converted to FAs -> transported to adipose -> TAG formation -> obesity
SGLT1 function
Galactose and glucose uptake
What causes galactosemia?
defect in GALT (galactose-1-phosphate uridyltransferase)
What happens in galactosemia?
Accumulation of galacitol -> cataracts, failure to thrive, liver failure
Where does PPP occur in the cell?
Cytosol
Two major products of PPP
Ribulose-5P, NADPH
What are some tissues with high PPP activity?
Lactating mammary glands, lungs, liver, phagocytes
What is ribulose-5P used for?
To make DNA and RNA
Two phases of PPP and whether they’re aerobic, reversible, and catabolic
Oxidative phase: irreversible, catabolic
Non-oxidative phase: reversible, anabolic
