Source: UWorld Question Bank
QID: 403358
Rationale:
Passage Excerpt: The passage states that PC5 processes itself by autocleavage when it arrives at the cell surface and that it does not act on other proteins until after autocleavage occurs.
Question:
Prior to reaching the cell surface, PC5 is:
A. an apoenzyme
B. a coenzyme
C. a holoenzyme
D. a zymogen
Answer:
D. a zymogen
Explanation:
I'm not sure how you feel about this one — either way, I think it's fine. The way I revised the card may be less broad, but I believe it provides a clearer and more focused explanation. PC5 is an enzyme that must be cleaved to become active. Although it's technically a precursor, I don’t think that label alone fully captures what a zymogen is.
That said, I think this either version still conveys the key concept.
Please let me know if you need any additional information.