Final answer:
The signal sequence is located at the N-terminal end of a peptide and plays a critical role in directing the peptide to the RER lumen during protein synthesis.
Step-by-step explanation:
The signal sequence is a specific series of amino acids found at the N-terminal end of a peptide. This sequence is crucial in directing the peptide to the lumen of the rough endoplasmic reticulum (RER). During the synthesis and elongation phases of protein translation, a signal recognition particle (SRP) recognizes the signal sequence as it emerges from the ribosome. The SRP temporarily halts translation, directs the ribosome to the RER membrane, and facilitates the attachment of the ribosome to a translocation channel. Once attached, translation resumes, allowing the growing polypeptide to enter the RER lumen. Inside the RER, the signal sequence is cleaved off by a signal peptidase, and the protein undergoes further folding and modification before being dispatched to its final destination.