Question

Scientists want to design fluorescent marker proteins for different cellular compartments using the Green Fluorescent Protein (GFP). This means that the GFP will be targeted and glow at the organelle of interest and they can use these to mark different organelles during fluorescence microscopy. To make these marker proteins, they take the sequence of GFP and add the desired sorting signal. A. GFP on its own is an excellent protein to use as an organelle marker protein because it is fluorescent. That means once a sorting signal is added it will light up in the indicated organelle. But there is an additional reason why GFP is well suited for this job. It doesn't have any additional sorting signals. Where might you expect to find GFP with nothing else added? Explain your answer. (2 mark) B. On the domain maps provided below, indicate the location and type (ER import, NLS, M6P) of all targeting sequences that you predict would have to be added for GFP to end up in the location given. Note: some sequences do not have a location requirement. These can be put in any portion of the protein If you don't need to add any targeting signals, clearly indicate this in your answer - a blank will NOT be considered as an answer for marks. (2 marks each): 1. GFP as a soluble ER resident marker protein N- -C 2. GFP as a mitochondrial matrix marker protein N- -C 3. GFP as a nuclear marker protein N- -C 4. GFP as a plasma membrane marker protein, with 1 transmembrane domain, and its N- terminus on the outside of the cell. N- -C