Signal transduction is a term used to describe the series of events that culminates in a cellular response to an extracellular signal or environmental stimuli. From the engagement of cell surface receptors to the activation of protein kinase cascades, this process involves a variety of molecular participants and regulates numerous cellular processes including cell survival/apoptosis, vesicular trafficking, cell differentiation, and cellular proliferation.
Cellular phosphorylation is regulated by two enzyme superfamilies - kinases and phosphatases and utilization of this post translational modification is at the heart of signal transduction. Activation of kinase and phosphatase cascades leads to strategic changes in intracellular phosphorylation and subsequently the function of target molecules allowing the cell and organism to respond appropriately to its surroundings. Disruption of signaling integrity invariably leads to abnormal phosphorylation, a consequence that often causes or promotes many human diseases.
