Question

A protein that has an internal ER-signal sequence and a nuclear localization might end up in the extracellular matrix. in the cytosol. inside a lysosome. o in the plasma membrane.

Answer 1

A protein that has an internal ER-signal sequence and a nuclear localization might end up in the plasma membrane. Translation of all proteins in a eukaryotic cell begins in the cytosol. As a protein is made, it passes step by step through a shipping "decision tree". At each stage, the protein is checked for molecular tags to see if it needs to be re-routed to a different pathway or destination.

The first major branch point comes shortly after translation starts. At this point, the protein will either remain in the cytosol for the rest of translation, or be fed into the plasma membrane as it is translated. Proteins are fed into the plasma membrane during translation if they have an amino sequence called a signal peptide.