ID #1584

In lecture you gave the example of insulin as the signal that needed to be degraded in a lysosome when the cell had brought in adequate amounts of glucose. If the insulin remains and continues to signal the cell that it should bring in glucose how does the cell know that it has enough glucose and should degrade the insulin?

In this particular example, there isn't some minimum amount of insulin allowed to remain before it gets degraded. As soon as the signal is received (and the action taken), the signaling molecule is removed via endocytosis. What keeps the signal going is the continual appearance of additional insulin molecules. Eventually, the pancreatic cells releasing the insulin will receive their own signal that it's time to stop sending it out, and since those remaining molecules will be degraded fairly quickly, the response is rapid.

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