Final answer:
RTKs binding to PI-3K activates signaling pathways essential for cell growth and division, with deregulation leading to diseases like cancer. This signaling mechanism is conserved across species, underlining its importance in cell biology.
Step-by-step explanation:
The function that Receptor Tyrosine Kinases (RTKs) serve by being able to bind phosphatidylinositol 3-kinase (PI-3K) is critical in cell signaling pathways that regulate various cellular responses, like metabolism, growth, and division. Upon the binding of growth factors to RTKs, a conformational change allows for autophosphorylation on tyrosine residues, which in turn provides docking sites for PI-3K. By binding to these activated RTKs, PI-3K is brought into proximity with its membrane lipid substrates, subsequently phosphorylating them and generating second messengers that activate downstream signaling proteins like AKT/PKB, which can lead to cell proliferation and survival.
This process is significant in the regulation of the cell cycle and can have implications in oncogenesis when dysregulated. For instance, mutations in the PI-3K or RTK pathway can cause aberrant signaling, contributing to uncontrolled cell proliferation, a hallmark of cancer.