Final answer:
A single-pass transmembrane protein targeted to the endomembrane system is marked by a cleaved N-terminal ER signal sequence and an internal stop-transfer sequence.
Step-by-step explanation:
A single-pass transmembrane protein that is destined for one of the organelles in the endomembrane system would be marked by a specific type of signal sequence. The correct answer is C. a cleaved N-terminal ER signal sequence and an internal stop-transfer sequence. An N-terminal signal sequence guides the ribosome translating the integral membrane protein to the rough endoplasmic reticulum (RER). Before the protein can pass completely through the membrane, a stop-transfer sequence traps it within the lipid bilayer, anchoring it as a transmembrane protein. These sequences are important because they determine the final destination and integration of the protein within the cell's membranes.