Phosphorylation
(Illustration
of transphosphorylation following receptor
clustering intrinsic kinase activity of hormone (SCF) receptor)
Advantages of
Phosphorylation: rapid, doesnt require
protein synthesis, easily reversed and thus regulated can easily be returned to unstimulated state which allows a time limit to be set, and allows the signaling pathway to get ready to receive another signal
First tier of transduction in lymphocytes is accomplished by protein kinases (first, tyrosine kinases, then serine/threonine kinases)
With antigen
receptors these will be Nonreceptor/Receptor
associated tyrosine kinases activated
following clustering (Src kinases, initiates cascade)
Some of the kinases will transphosphorylate