Which of the following events does not occur in rough endoplasmic reticulum?
- Cleavage of signal peptide
- Phospholipid synthesis
- Protein folding
- Protein glycosylation
Answer
(2) Phospholipid synthesis
Solution
As per NCERT, the rough endoplasmic reticulum (RER), bearing ribosomes on its surface, is actively involved in protein synthesis and secretion.
⇒ Proteins made on RER ribosomes enter the ER lumen, where the signal peptide is cleaved, the chain folds and glycosylation begins.
∵ The smooth endoplasmic reticulum (SER) is the major site for synthesis of lipids (phospholipids, steroids),
∴ phospholipid synthesis does not occur in RER.
Answer: (2)