This is some homework for my Cell and Molecular Biology class. Any answers would

Question

This is some homework for my Cell and Molecular Biology class. Any answers would be much appreciated!

1. (3 points) Imagine that you have engineered a set of genes, each encoding a protein with a pair of conflicting signal sequences that specify different compartments. If the genes were expressed in a eukaryotic cell, predict which signal would win out for the following combinations (where would the protein likely be). Think about where and when each signal is detected (e.g. during translation, after translation/folding) and predict wehre you would find the protein within a cell. Explain your reasoning:

a. Signals for import into peroxisomes and import into the ER

b. Signals for import into mitochondria and retention in the ER

c. Signals for import into the nucleus and export from the nucleus

Explanation / Answer

a. Signals for import into peroxisomes and import into the ER

ER. The signal for import into the ER is located at the N-terminus of the protein and functions before the protein is fully synthesized, whereas the signal for peroxisome import is at the C-terminus and functions after the protein has been released from the ribosome.

b. Signals for import into mitochondria and retention in the ER

Mitochondria. In order to be retained in the ER the protein must first be imported into the ER. Without a signal for ER import, the ER retention signal could not function.

c. Signals for import into the nucleus and export from the nucleus

A protein with signals for both nuclear import and nuclear export would shuttle between the cytosol and the nucleus.

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