The function of Ensembl gene identifier ENSG00000101294 (HM13, histocompatibility minor 13) is as follows. Catalyzes intramembrane proteolysis of signal peptides that have been removed from precursors of secretory and membrane proteins, resulting in the release of the fragment from the ER membrane into the cytoplasm (PubMed:12077416, PubMed:15716490, PubMed:17517891). Required to generate lymphocyte cell surface (HLA-E) epitopes derived from MHC class I signal peptides (PubMed:11714810). May be necessary for the removal of the signal peptide that remains attached to the hepatitis C virus core protein after the initial proteolytic processing of the polyprotein (PubMed:12145199). Involved in the intramembrane cleavage of the integral membrane protein PSEN1 (PubMed:11714810, PubMed:12077416, PubMed:14741365). Cleaves the integral membrane protein XBP1 isoform 1 in a DERL1/RNF139-dependent manner (PubMed:25239945). May play a role in graft rejection (By similarity). {ECO:0000250|UniProtKB:Q9D8V0, ECO:0000269|PubMed:11714810, ECO:0000269|PubMed:12077416, ECO:0000269|PubMed:12145199, ECO:0000269|PubMed:14741365, ECO:0000269|PubMed:15716490, ECO:0000269|PubMed:17517891, ECO:0000269|PubMed:25239945}.