Make sure that your cuts are as accurate as possible. If you need to trim areas, you can simply run the knife along the edge. Hold the knife so that the blade bites slightly into the edge. This can be a tedious process so try to get it right the first time.
When insulin binds to the receptor, it is thought to cause a change in shape that is propagated inside the cell, activating the tyrosine kinases. The details are still a mystery and an area of active research.
G proteins relay their signal on the inside surface of the cell membrane. The process starts when a receptor binds to its proper hormone or neurotransmitter, such as adrenaline. This changes the shape of the receptor, and it binds to the inactive three-chain G protein inside.