What is the relationship between GLUT4 and insulin signaling in animal cells?

• A. GLUT4 is an enzyme that breaks down insulin in the cytoplasm.
• B. GLUT4 is a transcription factor activated by insulin to increase gene expression.
• C. GLUT4 is a receptor that binds directly to insulin on the cell surface.
• D. GLUT4 is a glucose transporter that is translocated to the cell membrane in response to insulin signaling.

Answer: (D)

Verified step by step guidance

1. Understand the role of GLUT4: GLUT4 is a glucose transporter protein found in animal cells, specifically in tissues like muscle and fat. It facilitates the uptake of glucose from the bloodstream into cells.
2. Learn about insulin signaling: Insulin is a hormone that regulates glucose levels in the blood. When insulin binds to its receptor on the cell surface, it triggers a signaling cascade inside the cell.
3. Explore the connection between insulin and GLUT4: Insulin signaling leads to the activation of intracellular pathways, such as the PI3K-Akt pathway, which ultimately causes GLUT4-containing vesicles to move toward the cell membrane.
4. Understand translocation: Once the GLUT4 vesicles reach the cell membrane, GLUT4 is inserted into the membrane, allowing glucose to be transported into the cell from the extracellular space.
5. Clarify the correct answer: GLUT4 is not an enzyme, transcription factor, or receptor. It is a glucose transporter that is translocated to the cell membrane in response to insulin signaling, enabling glucose uptake into the cell.