A secretory protein destined for the endoplasmic reticulum is recognized co-translationally. Which component binds to the signal peptide as it emerges from the ribosome and directs the ribosome to the ER membrane?
- A Signal recognition particle (SRP) ✓
- B Sec61 translocon complex
- C Docking protein (SRP receptor)
- D Signal peptidase
Correct answer: A. Signal recognition particle (SRP)
Explanation
The signal recognition particle (SRP) binds the hydrophobic signal peptide as it exits the ribosomal tunnel, pauses translation, and targets the ribosome-nascent chain complex to the SRP receptor on the ER membrane. The Sec61 complex forms the translocation channel, the docking protein is the SRP receptor itself, and signal peptidase cleaves the signal peptide after translocation begins.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.