You Are Studying a Protein in Salmonella Typhimurium That You

Multiple Choice

You are studying a protein in Salmonella typhimurium that you believe is a toxin. Whenever you attempt to purify the protein from lysed cell cultures, you get two forms of the protein. One form is smaller than the other and is missing 15 amino acids from the N-terminus compared to the larger form. This leads you to hypothesize that

A) there are two termination sites in the mRNA.
B) the protein requires chaperonins to fold properly.
C) the protein is secreted and folds outside of the cell.
D) you need to re-do the experiment because there should only be one form.