English: Mechanism of action of Insulin: Excreted from the pancreas,
insulin circulates through the blood (λ=30min) before binding to an
insulin receptor (IR) expressed on the surface of
myocytes,
adipocytes and
hepatocytes. Once insulin binds to the receptor,
phosphorylation takes place and attaches to the beta-subunit, thus initiating the transduction process. A protein binds to the phosphorylated receptor protein, becoming phosphorylated as well. Once the protein detaches from the receptor protein, the signal has successfully been transported from the receptor to the newly active protein. Through a series of kinase proteins, the proteins are constantly being phosphorylated and activated. At the end of the transduction process, the activated protein binds to the
PIP2 proteins embedded in the membrane. By doing so, the initial signal has successfully transmitted the extracellular signal. As a result, another protein is activated, later activating the storage vesicles found within the cell. Upon activation, the vesicle is transported to the membrane, where its membrane becomes integrated within the cellular membrane under a process known as phagocytosis. The
Glucose transporter type 4 (GLUT4) protein channels that were once embedded in the storage vesicles are now embedded in the cellular membrane. Much more (×100,000?) Glucose can now flow into the cell through these glucose transport channels.
Source information:
http://vcell.ndsu.nodak.edu/animations/insulinsignaling/movie-flash.htm