You prepare radioactivley labelled ribosomal subunits and you microinject them into cells that you are culturing in the laboratory. At different times after you inject the subunits, you take a small amount of cells and analyze them by electron microscopy. You find very soon after injection, the labelled subunits are assembled into cytosolic ribosomes. As more time passes, labelled subunits can be seen in both cytosolic and ER-bound ribosomes.
You repeat the experiment except that at the same time you inject ribosomal subunits into the cells, you also inject the inhibitor of the ER translocon. Where will you find the labelled ribosomal subunits in the cell, both immediatley after the injection and some time thereafter?
You again repeat this experiment except at the same time you inject ribosomal subunits into the cells you also inject a large amount of a short peptide containing an ER import sequence. Where will you find the labelled ribosomal subunits in the cell, both immediatley after the injection and some time thereafter?
For the second question I believe immediatley you would find it in the ER and then it will then be later exported into the Golgi. Is this correct?
Ideas are expressed.
If we inhibit the ER translocon, ribosomes will not be able to bind to the ER membrane as they normally would do when called upon to synthesize proteins with various signal sequences. Therefore, if we inhibit the ER translocon complex, the ribosomes will remain in the cytosol, whether immediately after injection or some time thereafter.
If we repeat the experiment with lots of a short peptide containing an ER import sequence, we'll ...
The location of ribosomes is assessed.