Which of the following is a function of a signal peptide?

A) To bind RNA polymerase to DNA and initiate transcription

B) To direct mRNA molecules into the cisternal space of the ER

C) To terminate translation of the messenger RNA

D) To translocate polypeptides across the ER membrane

D) To translocate polypeptides across the ER membrane is a correct answer.

Explanation:

The signal peptide is a short stretch of amino acids, present at N terminus of nascent protein.

Function of a signal peptide is to guide the protein where to go and is to transport the protein to the ER membrane.

When the protein is reserved for the secretion, then signal peptide guide the protein to translocate polypeptides across the Endoplasmic membrane, where it get mature and prepare for the secretion.

Thus option (D) To translocate polypeptides across the ER membrane is correct answer.