Final Answer:
The signal sequence from nascent polypeptides is removed by c) Signal peptidase
Step-by-step explanation:
The removal of the signal sequence from nascent polypeptides in the rough endoplasmic reticulum (ER) is carried out by the enzyme known as c) signal peptidase. This process is crucial for the maturation and proper functioning of proteins targeted to cellular membranes or secretory pathways.
As a nascent polypeptide is being synthesized by ribosomes on the rough ER, a signal sequence guides it to the ER membrane. Signal peptidase recognizes and cleaves this signal sequence, allowing the mature polypeptide to be translocated into the ER lumen or integrated into the ER membrane. This enzyme's specificity for signal sequences ensures the accurate processing of proteins and their correct localization within the cell.
Unlike the options DNA polymerase, RNA polymerase, and ribonuclease, which are primarily involved in nucleic acid-related processes, signal peptidase is specialized for the post-translational modification of proteins in the secretory pathway. Understanding this enzymatic activity sheds light on the intricate molecular mechanisms that govern protein synthesis, processing, and trafficking in eukaryotic cells.