Endoplasmic Reticulum Aminopeptidases

Work in Progress Updated Feb 20, 2026

ERAP is located on chromsome 5.

ERAP1

ERAP2

Property	ERAP1	ERAP2
Molecular ruler	Yes (C-term pocket + catalytic site)	No (lacks C-term regulatory pocket)
Peptide length preference	Trims 9-16mers efficiently (stops at ~8-9 residues)	Can trim <=8mers (may destroy epitopes)
C-terminal preference	Requires hydrophobic C-terminus for activation	No C-terminal residue requirement
N-terminal preference	Hydrophobic (Leu, Phe, Try, Met)	Basic (Arg, Lys) via acidic S1
Conformation	Open:closed switch	Substrate sequestration in internal cavity