GPI inositol-deacylase that catalyzes the remove of the acyl chain linked to the 2-OH position of inositol ring from the GPI- anchored protein (GPI-AP) in the endoplasmic reticulum (PubMed:24784135, PubMed:38167496). Initiates the post-attachment remodeling phase of GPI-AP biogenesis and participates in endoplasmic reticulum (ER)-to-Golgi transport of GPI-anchored protein (PubMed:24784135, PubMed:38167496). {ECO:0000269|PubMed:24784135, ECO:0000269|PubMed:38167496}. This is the function of PGAP1 (post-GPI attachment to proteins inositol deacylase 1, ENSG00000197121).