How does insulin facilitate glucose entry into skeletal muscle fibers and adipocytes?
Answer and explanation
Correct answer: A. By mobilizing intracellular vesicles containing GLUT4 transporters to fuse with the plasma membrane
In skeletal muscle and adipose tissue, glucose uptake is insulin-dependent and mediated by the glucose transporter isoform GLUT4. Binding of insulin to its receptor tyrosine kinase activates the IRS-1/PI3K/Akt signaling pathway, promoting translocation and fusion of intracellular GLUT4-containing storage vesicles with the plasma membrane, thereby dramatically increasing the rate of facilitated glucose diffusion into the cell.
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