Endocrinology/hormones question

[agp]

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Is there a website that shows how hormones work on a cellular level?
For example, insulin must bind to a cell receptor because it cannot diffuse through the cell, what's the receptor called? Receptor then activates a second messenger, what is the messenger called? Second messenger activates glut4, etc etc.

 

[Baboo Bhaiya]

http://www.youtube.com/watch?v=WzpLGZKQjZY&feature=player_embedded#t=85

http://www.medbio.info/Horn/Time 3-4/Insulin's Mechanism of Action.htm

Google "Insulin Mechanism"

Insulin acts in 2 ways:
1. It can activate transcription and translation of genes needed for cell division
2. It can increase the number of glucose transporters on the cell membrane so that the cell can uptake excess glucose

For the purposes of MCAT, you only have to know the 2nd function. INSULIN INCREASES GLUCOSE UPTAKE.

I do not know if there is any other word for the insulin receptor than just Insulin Receptor. I do know that the insulin receptor is a tyrosine kinase and there is a long pathway between activation of the insulin receptor and increase glucose transporter proteins on the membrane. However, majority of the proteins in this pathway are kinases (they phosphorylate).

I have typically heard the term second messengers in relation with G-proteins so I am not sure if you would call the kinases second messengers, since the insulin receptor is not a g-protein. But, some of those kinases are IRS1, Grb2, Sos, etc. etc. You don't have to worry about them for MCAT.

GLut 4 is actually the glucose transporter. So the end result of the insulin pathway is increased GLUT 4 on the membrane in order to increase glucose uptake.