polypeptide hormone

[faith hopelove]

---

Members do not see this ad.

This question is from the independent questions in TPR workbook. This is number 8:

Clathrin, a substance that aggregates on the cytoplasmic side of cell membranes, is responsible for the coordinated pinching off of membrane in receptor-mediated endocytosis. A lipid-soluble toxin that inactivates clathrin would be associated with:

A. reduced delivery of polypeptide hormones to endosomes.
B. increased secretion of hormone into the extracellular fluid.
C. increased protein production on the rough ER.
D. an increase in ATP consumption.

The answer is A. From what I know about peptide hormones, it does not enter into the cell but is like a primary messenger which leads to a secondary messenger that activates enzymes already present in the cell. If peptide hormones do not enter into the cell then how is it that A is the answer.

 

[scrub2scrubs]

Yeah you are right, from what I know pretty much all peptide hormones act as primary messengers. I am sure there may be some example of a peptide hormone that is brought into the cell. But I guess the point they just wanted to get across is that when clathrin is disrupted, you can't endocytose things into the cell. Poorly worded question.

 

[mcloaf]

Consider the cell that manufactures peptide hormones. It will require clathrin to bud endosomes containing newly made peptide hormone from the golgi. You guys are right that peptide hormones act on plasma membrane receptors to initiate second messenger cascades. Agree that it could be a better written question.