Fig. 3.
From: Targeting RNA N6-methyladenosine modification: a precise weapon in overcoming tumor immune escape
Overview of human leukocyte antigen (HLA)-I antigen processing and presentation machinery. Peptides are generated by the degradation of endogenous proteins via the proteasomal pathway. The peptides are then translocated by transporters associated with the antigen processing (TAP) in the endoplasmic reticulum (ER). In the ER lumen, peptides can be further trimmed by ER aminopeptidase 1 (ERAP1) and ERAP2. The peptide-loading complex, comprising ERp57 and calreticulin (CALR), helps the loading and folding of HLA-I molecules with peptide and β2-microglobulin (β2M). Tapasin assesses peptides for stable binding to the complex formed by the HLA-I heavy chain α1 and α2 domains. CALR, calreticulin; ER, endoplasmic reticulum; ERAP1, ER aminopeptidase 1; HLA-I, human leukocyte antigen-I; TAP, transporters associated with antigen processing; β2M, β2-microglobulin