Question

You have replaced the C-terminus of the nuclear receptor superfamily protein for cortisol with the C-terminus of the nuclear receptor superfamily protein for vitamin D; what do you expect to observe in cells that express this chimeric receptor?

a) cells with activate cortisol responsive genes when exposed to cortisol
b) cells will activate cortisol responsive genes when exposed to vitamin D
c) cells will activate vitamin D responsive genes when exposed to cortisol
d) There will be no changes to transcription in response to any signal since the chimeric nuclear receptor superfamily protein will not bind DNA.

Answer 1

Cells with a chimeric receptor combining the C-terminus for vitamin D with the cortisol receptor are expected to activate cortisol responsive genes when exposed to vitamin D.

Step-by-step explanation:

When you replace the C-terminus of the nuclear receptor for cortisol with the C-terminus of the nuclear receptor for vitamin D, the chimeric receptor will likely exhibit altered hormone binding specificity. Since the C-terminus of a nuclear receptor is generally responsible for hormone binding, the chimeric receptor would potentially bind vitamin D instead of cortisol. Consequently, when cells expressing this chimeric receptor are exposed to vitamin D, they are expected to activate cortisol responsive genes, because the remaining parts of the receptor, including the DNA-binding domain, are still designed to interact with cortisol response elements. In contrast, these cells would not activate vitamin D responsive genes when exposed to cortisol, as the receptor's ability to bind cortisol would be compromised. Therefore, the correct answer is b) cells will activate cortisol responsive genes when exposed to vitamin D.