Insulin and GLUT4 glucose transporters

[nautica]

The presence of insulin increases the activity of the GLUT4 glucose transporters and not the actual number of the transporters.

In a freeze fracture, it appeared that the GLUT4s moved from the internal membrane into the plasma membrane.

I am asked to deduce the mechanism by which glucose transport by GLUT4 is increased in insulin treated cells.

Is the mechanism, just that the insulin causes this migration or is it more complex than this???

Thanks
Nautica

[nautica]

Monique and Moonbear, I know that at least 1 of you know the answer to this question. :smile:

[Moonbear]

The one thing I'm pretty certain of is that your instructor (I'm assuming this is for a class the way you asked it) is providing very current examples. There's an article on this topic that came out this month (though doesn't directly answer your question, I thought you might find it interesting since it relates to your coursework).

Coster AC, Govers R, James DE.
Insulin Stimulates the Entry of GLUT4 into the Endosomal Recycling Pathway by a Quantal Mechanism.
Traffic. 2004 Oct;5(10):763-71.

There may be a complex answer, but right now, it seems only a simple one can be given (unless part of the "deduction" exercise is to speculate further on possible pathways that are not yet known). Anyway, the title of the article I referenced gives you a hint. Think about endosomes. I think that's what the question is trying to get at.

[nautica]

Thanks, I will check it out.