Exam question no one could answer

[willrider]

So out of my macromolecular structure and function class of fifty something people, no one got this question completely correct on the last exam, and now all-or-nothing extra credit is being offered for the correct response.

Here's the question: In the Ormo paper (www-bioc.rice.edu/Bioch/Phillips/Papers/gfpbio.html) they expressed GFP in bacteria instead of jellyfish. Could you make a functional aequorin in a similar way? Why or why not?

I received partial credit for stating that it could be possible if the cell could be engineered to maintain a high concentration of the Ca2+ cofactor intracellularly, and others also received some credit for arguments based on prosthetic groups being necessary, but the professor stated that these answers didn't really hit the nail on the head.

Any help would be greatly appreciated. Thanks everyone.