HM13

Minor histocompatibility antigen H13 is a is_associated_with::protein that in humans is encoded by the HM13 is_associated_with::gene.

Function
The minor histocompatibility antigen 13 is a nonamer peptide that originates from a protein encoded by the H13 gene. The peptide is generated by the is_associated_with::cytosol by the is_associated_with::proteasome, enters the is_associated_with::endoplasmic reticulum (ER) lumen by the is_associated_with::transporter associated with antigen processing (TAP) and is presented on the cell surface on H2-Db major histocompatibility anigen I (is_associated_with::MHC I) molecules. The alloreactivity, which leads to is_associated_with::transplant rejection in mice, is conferred by Val/Ile polymorphism in the ‘SSV(V/I)GVWYL’ peptide. The orthologue gene in humans is called HM13. If a related polymorphism exists, and if the HM13 serves as a is_associated_with::Minor histocompatibility antigen, however, remains to be addressed.

The protein encoded by the M13/HM13 gene is the is_associated_with::signal peptide peptidase (SPP), an ER-resident is_associated_with::intramembrane protease. SPP localizes to the is_associated_with::endoplasmic reticulum, catalyzes intramembrane proteolysis of some signal peptides after they have been cleaved from a preprotein. This activity is required to generate signal sequence-derived human lymphocyte antigen-E epitopes that are recognized by the immune system, and to process hepatitis C virus core protein. The encoded protein is an integral membrane protein with sequence motifs characteristic of the presenilin-type aspartic proteases. Multiple transcript variants encoding several different isoforms have been found for this gene.