What does "heterotrimer" mean?

Question

a receptor that has two subunits that phosphorylate each other

a protein that activates another molecule by phosphorylating it

a protein that has three subunits, all the same polypeptide

a protein that has three subunits, all different polypeptides

Answer 1

Answer:

A protein that has three subunits, all different polypeptides

Explanation:

The prefix "hetero-" in biology typically refers to different. Meanwhile, "-trimer" refers to how many subunits there are in a protein, in this case being three. Thus, by combining those, we know it refers to a protein with three subunits, all composed of different polypeptides.

For perspective, homotrimer stands for a protein with three subunits, all having the same polypeptides. Heterotetramer would stand for a protein that has four subunits, all different polypeptides. There are countless examples, though this demonstrates the trend.