B2.045 Prework 1 Biological Differences of GLUT Isoforms Flashcards Preview

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Flashcards in B2.045 Prework 1 Biological Differences of GLUT Isoforms Deck (8)
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1

how do GLUT 1-4 and GLUT 5,7 differ?

GLUT 1-4 stereo-selective for glucose
GLUT 5,7 stereo-selective for fructose

2

characterize GLUT 1-4

passive, facilitated diffusion requires sugar gradient
bi-directional transport

3

how does GLUT appear to function?

alternating conformations between cytoplasmic and extracellular facing modes

4

why do we think GLUT has alternating conformations?

alternative drugs can block the two different protein sites

5

how do the 12 GLUT isoforms differ?

substrate specificity
substrate Km
tissue distribution
regulation

6

where is GLUT2 located?

liver, islets, kidney, small intestine

7

why is the GLUT2 Km so high compared to normal circulating glucose in the small intestine? (17 mM vs. 5 mM)

this makes GLUT2 more useful in the fasting state and prevents the channel from running backwards from blood into cell

8

what is the function of GLUT2 in the pancreas?

15-25% activity
can sense changes in blood glucose with a 1:1 correlation
respond with insulin release