What will happen if flippase is inactivated and scramblase is activated at the plasma membrane?

What will happen if flippase is inactivated and scramblase is activated at the plasma membrane?

• A. Nothing will happen
• B. Phospholipids will no longer flex their fatty acid tails
• C. Phosphatidylserine will transfer from the cytosolic to the extracellular layer
• D. The two monolayers will have asymmetric distributions

Answer: (C)

When flippase is inactivated and scramblase is activated at the plasma membrane, the correct outcome involves the movement of phospholipids across the membrane layers. Flippase typically functions to maintain asymmetry by actively transporting specific phospholipids, like phosphatidylserine, from the outer layer of the membrane to the inner layer. When flippase is not functioning, this process is disrupted. On the other hand, scramblase facilitates the bidirectional movement of phospholipids between the inner and outer layers of the membrane, allowing for a more random distribution. When scramblase is activated, it promotes the transfer of phosphatidylserine from the cytosolic (inner) layer to the extracellular (outer) layer of the plasma membrane. This transfer is particularly important in various physiological processes, including apoptosis, where the externalization of phosphatidylserine serves as a signal for cellular changes. Therefore, inactivation of flippase combined with the activation of scramblase results in phosphatidylserine moving to the outer layer, which confirms the correctness of this answer.

When flippase is inactivated and scramblase is activated at the plasma membrane, the correct outcome involves the movement of phospholipids across the membrane layers. Flippase typically functions to maintain asymmetry by actively transporting specific phospholipids, like phosphatidylserine, from the outer layer of the membrane to the inner layer. When flippase is not functioning, this process is disrupted.

On the other hand, scramblase facilitates the bidirectional movement of phospholipids between the inner and outer layers of the membrane, allowing for a more random distribution. When scramblase is activated, it promotes the transfer of phosphatidylserine from the cytosolic (inner) layer to the extracellular (outer) layer of the plasma membrane.

This transfer is particularly important in various physiological processes, including apoptosis, where the externalization of phosphatidylserine serves as a signal for cellular changes. Therefore, inactivation of flippase combined with the activation of scramblase results in phosphatidylserine moving to the outer layer, which confirms the correctness of this answer.