The function of PIGO (phosphatidylinositol glycan anchor biosynthesis class O, ENSG00000165282) is as follows. Catalytic subunit of the ethanolamine phosphate transferase 3 complex that transfers an ethanolamine phosphate (EtNP) from a phosphatidylethanolamine (PE) to the 6-OH position of the third alpha- 1,2-linked mannose of the a 2-acyl-6-[alpha-D-mannosyl-(1->2)-alpha-D- mannosyl-(1->6)-2-phosphoethanolamine-alpha-D-mannosyl-(1->4)-alpha-D- glucosaminyl]-1-(1-radyl,2-acyl-sn-glycero-3-phospho)-1D-myo-inositol (also termed H6) intermediate to generate a a 2-acyl-6-[6- phosphoethanolamine-alpha-D-mannosyl-(1->2)-alpha-D-mannosyl-(1->6)-2- phosphoethanolamine-alpha-D-mannosyl-(1->4)-alpha-D-glucosaminyl]-1-(1- radyl,2-acyl-sn-glycero-3-phospho)-1D-myo-inositol (also termed H7) and participates in the tenth step of the glycosylphosphatidylinositol- anchor biosynthesis. {ECO:0000305|PubMed:24049131, ECO:0000305|PubMed:24417746, ECO:0000305|PubMed:28337824}.