In MHC class I antigen presentation, peptides derived from cytosolic proteins are transported into the endoplasmic reticulum via a specific transporter for loading onto MHC I molecules. What is the name of this transporter?
- A TAP (Transporter associated with Antigen Processing) ✓
- B MIIC (MHC class II compartment)
- C Invariant chain (CD74)
- D LAMP-1 transporter
Correct answer: A. TAP (Transporter associated with Antigen Processing)
Explanation
The TAP heterodimer (TAP1/TAP2) transports peptides generated by the cytosolic proteasome into the ER lumen, where they are loaded onto MHC class I molecules with assistance from tapasin (TAPBP), calreticulin, and ERp57. MHC I–peptide complexes then travel to the cell surface to present endogenous antigens to CD8+ cytotoxic T cells. Herpes simplex virus ICP47 blocks TAP to evade immune surveillance. The MIIC compartment and invariant chain are components of MHC class II processing. LAMP-1 is a lysosomal membrane protein unrelated to antigen transport.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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