Minor histocompatibility antigens in human stem cell transplantation J.H.Frederik Falkenburg, Lisette van de Corput, Erik W.A Marijt, Roel Willemze  Experimental Hematology  Volume 31, Issue 9, Pages 743-751 (September 2003) DOI: 10.1016/S0301-472X(03)00190-5

Figure 1 Proteins expressed in the cytosol or nucleus are degraded by the proteasome into smaller peptide fragments. These peptides can be N-terminally trimmed by aminopeptidases and subsequently translocated by the peptide pump “transporter in antigen processing” (TAP) over the membrane of the endoplasmic reticulum (ER). HLA class I molecules are synthesized and retained in the ER lumen until successful peptide binding occurs. These peptide/HLA complexes are subsequently transported to the plasma membrane. Experimental Hematology 2003 31, 743-751DOI: (10.1016/S0301-472X(03)00190-5)