The animation to the right is meant to depict a tyrosine kinase receptor like that used by insulin. Following binding of hormone, the receptor undergoes a conformational change, phosphorylates itself, then phosphorylates a variety of intracellular targets.

Sorry, your browser does not support Java
Adapted from http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/moaction/surface.html.

Also see Physiologic Effects of Insulin