Component of the glycosylphosphatidylinositol-anchor (GPI- anchor) transamidase (GPI-T) complex that catalyzes the formation of the linkage between a proprotein and a GPI-anchor and participates in GPI anchored protein biosynthesis (PubMed:11483512, PubMed:29100095, PubMed:34576938, PubMed:35165458, PubMed:35551457, PubMed:37684232, PubMed:9468317). Binds GPI-anchor (PubMed:37684232). {ECO:0000269|PubMed:11483512, ECO:0000269|PubMed:29100095, ECO:0000269|PubMed:34576938, ECO:0000269|PubMed:35165458, ECO:0000269|PubMed:35551457, ECO:0000269|PubMed:37684232, ECO:0000269|PubMed:9468317}. This is the function of Ensembl gene identifier ENSG00000197858 (GPAA1, glycosylphosphatidylinositol anchor attachment 1).