insulin pathways

[nickname]

insulin is a hormone that travels thorugh the blood to cells, triggering the cells to alter metabolic proceses. Insulin does not enter target cells, but instead binds to an extracellular receptor, starting a signal transduction pathway in the cell.

I have to put the steps in order from the circulation of insulin in the blood to the alteration of the cell's metabolism.

a) the receptor tyrosine kinase phosphorylates another receptor tyrosine kinase
b)insulin binds extracellularly to the insulin receptor
c) SH2-containing proteins are activated by the phosphorylated receptor tyrosine kinase.
d) proteins that contain an SH2 domain recognize activated receptor tyrosine kinases.


My answer is the following:

insulin circulates blood: b)insulin binds extracellularly to the insulin receptor, c) SH2-containing proteins are activated by the phosphorylated receptor tyrosine kinase, d) proteins that contain an SH2 domain recognize activated receptor tyrosine kinases, a) the receptor tyrosine kinase phosphorylates another receptor tyrosine kinase.

Is my answer correct? Thank you for your help!

[JackBean]

1) the protein must first recognize the receptor, before it can be activated (how could it be activated in the cytosol? And why would it bind afterwards?)

2) I think there are first several Tyr kinases, before the SH2 proteins come into play...