Which is the correct order of activities showcased by endogenous antigens?

Question

Which is the correct order of activities showcased by endogenous antigens?

i) Peptide binding to MHC Class I

ii) Transport to Endoplasmic Reticulum

iii) Generation of Peptide from proteolysis

1. A. i-ii-iii
2. B. iii-ii-i (Correct answer)
3. C. ii-iii-i
4. D. i-iii-ii

Correct Answer

Option B — iii-ii-i

Detailed Solution & Explanation

The correct answer is iii-ii-i.

Key Points

• Endogenous antigen processing: iii (proteasome generates peptides from cytosolic proteins) -> ii (peptides transported to ER via TAP transporter) -> i (peptides bind MHC Class I in ER, then surface presentation).