You isolate the rough ER from the cytoplasm and purify the m

You isolate the rough ER from the cytoplasm and purify the mRNAs attached to it. Circle any of the proteins you would expect such mRNA to encode; explain why the others are not expected on the ER. a. soluble secreted proteins b. ER trans-membrane proteins c. integral plasma membrane proteins d. endosomal lysosomal proteins e. nuclear proteins f. SRP-receptor proteins g. 7SLRNA-associated-proteins

Solution

D. Endosomal and lysosomal protein.

The rough endoplasmic reticulum (RER) which is continuous with the outer membrane of the nuclear envelope plays an important role in the sorting of proteins destined for various other locations in the cell, like the Golgi apparatus, the lysosomes and the plasma membrane. So most probably that mRNA should encode the lysosomal protein.