Is GLUT2 insulin independent?

[Cundiff1080]

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In FA 2013, it says, GLUT1 (insulin independent glucose uptake), GLUT2 (bidirectional), GLUT4(insulin dependent). Then the BRICK L mnemonic includes the liver and intestine as insulin-independent glucose uptake, but not the beta islet cells. So does that mean GLUT2 is insulin independent as well?

Thanks.

 

[dfib slim]

FA 2014 specifically says it's insulin independent

 

[Transposony]

GLUT 2 has to be insulin dependent independent since unless glucose enters beta cells via GLUT 2 it won't be able to make the ATP required to close the K+ channel which is required to depolarize the membrane for Ca+ channels to open and Ca+ to enter the cell to bring about insulin release.

 

[dfib slim]

GLUT 2 has to be insulin dependent since unless glucose enters beta cells via GLUT 2 it won't be able to make the ATP required to close the K+ channel which is required to depolarize the membrane for Ca+ channels to open and Ca+ to enter the cell to bring about insulin release.

Are you saying the beta cells require insulin for glucose uptake to produce more insulin?

 

[Transposony]

Are you saying the beta cells require insulin for glucose uptake to produce more insulin?

My apologies. It was a typo.
It should read: GLUT 2 has to be insulin independent since unless glucose enters beta cells via GLUT 2 it won't be able to make the ATP required to close the K+ channel which is required to depolarize the membrane for Ca+ channels to open and Ca+ to enter the cell to bring about insulin release.

 

[aspiringmd1015]

whoops

 

[scoKraz4]

Glut 2 km in beta islet is HIGH -->low affinity. This is so that normal glucose levels don't trigger insulin release.

 

[Je Suis Banane]

Glut 2 km in beta islet is HIGH -->low affinity. This is so that normal glucose levels don't trigger insulin release.

Just to add on to this; it's my understanding that GLUT 2, the receptor found in hepatocytes and B-islet cells, has a high Km (low affinity) because hepatocytes use glucose primarily for storage - and it makes no sense to store glucose unless you've just eaten a big meal and your glucose levels are high enough to bind with this low affinity receptor) - whereas muscle and adipose respond to glucose in peripheral blood with GLUT 4 (and GLUT 1? not sure about this) and have a much lower Km (higher affinity) because they require a relatively constant supply of glucose so even in times of fasting they pull in glucose from the blood. I think it's true that GLUT 2 transporters and glucokinase serve as insulin sensors for glucose release from islet cells in the pancreas, it's just not the first thing that comes to mind when justifying their affinity.