Question

You are working in a research lab analyzing cells isolated from the lungs of Cystic fibrosis patients. In one of the samples you find that the CFTR protein is stuck in the ER. Which of the following COULD BE a reason for your observation.

		the CFTR protein is misfolded
		the CFTR protein is lacking a "go to cell membrane" signal
		the CFTR mRNA is not spliced properly
		the CFTR protein is not phosphorylated properly

Answer 1

The answer is: the CFTR protein is lacking a "go to cell membrane" signal.

Explanation :

Every protein has a particular amino acid sequence at the N terminal of protein. This N terminal sequence is known as signal peptide. This sequence is responsible for targetting the protein to another organelle in the cells or to its particular destination in the cell compartment.

when the signal peptide is not found in the CFTR protein, then it will not be destined to its particular action. Hence the protein stuckes in the cells.