Endoplasmic Reticulum Aminopeptidase 2 (ERAP2)

Aminopeptidases hydrolyze N-terminal amino acids of proteins or peptide substrates. Major histocompatibility complex (MHC) class I molecules rely on aminopeptidases such as ERAP1 and LRAP to trim precursors to antigenic peptides in the endoplasmic reticulum (ER) following cleavage in the cytoplasm by tripeptidyl peptidase II (TPP2) The deduced full-length protein contains 960 amino acids and has a calculated molecular mass of 123 kD. It shares 43% and 49% identity with PLAP and ERAP1, respectively, and contains a hydrophobic N-terminal region, zinc metallopeptidase (M1) motifs, and 9 potential N-glycosylation sites. The truncated form, LRAP(s), contains 532 amino acids. Northern blot analysis using the full-length LRAP cDNA as probe detected ubiquitous expression of a 6.7-kb transcript, with relatively high expression in spleen and leukocytes.