Final answer:
GLUT4 allows for glucose uptake into cells through a pathway initiated by the binding of insulin to its receptor, which causes GLUT4-containing vesicles to merge with the plasma membrane, facilitating glucose entry into the cell.
Step-by-step explanation:
The pathway by which GLUT4 allows for glucose uptake is directly influenced by the hormone insulin. Upon insulin binding to its receptor on the plasma membrane, a series of events ensues resulting in the translocation of GLUT4. These events begin with the activation of a tyrosine kinase receptor, which leads to the phosphorylation of IRS-1 and a cascade of protein activation within the cell. As a result, vesicles containing GLUT4 merge with the plasma membrane, a process known as vesicle fusion, allowing GLUT4 transporters to facilitate the diffusion of glucose into the cell. This mechanism is crucial for controlling blood glucose levels and is implicated in the pathology of type 2 diabetes, where the insulin response can become dampened, leading to increased blood glucose concentrations.
Moreover, insulin stimulates other metabolic pathways such as glycogen synthesis, glycolysis, and fatty acid synthesis through a similar mechanism of protein phosphorylation and activation.