Scramblase that mediates the translocation of glucosaminylphosphatidylinositol (alpha-D-GlcN-(1-6)-(1,2-diacyl-sn-glycero-3-phospho)-1D-myo-inositol, GlcN-PI) across the endoplasmic reticulum (ER) membrane, from the cytosolic leaflet to the luminal leaflet of the ER membrane, where it participates in the biosynthesis of glycosylphosphatidylinositol (GPI) (PubMed:35344438). GPI is a lipid glycoconjugate involved in post-translational modification of proteins (PubMed:35344438). Can also translocate 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol) (phosphatidylinositol or PI), as well as several other phospholipids (1,2-diacyl-sn-glycero-3-phosphocholine, 1,2-diacyl-sn-glycero-3-phosphoethanolamine), and N-acetylglucosaminylphosphatidylinositol (GlcNAc-PI) in vitro (PubMed:35344438). an alpha-D-GlcN-(1->6)-(1,2-diacyl-sn-glycero-3-phospho)-1D-myo-inositol(in) = an alpha-D-GlcN-(1->6)-(1,2-diacyl-sn-glycero-3-phospho)-1D-myo-inositol(out) 6-(alpha-D-glucosaminyl)-(1-octadecanoyl,2-(9Z)-octadecenoyl-sn-glycero-3-phospho)-1D-myo-inositol(in) = 6-(alpha-D-glucosaminyl)-(1-octadecanoyl,2-(9Z)-octadecenoyl-sn-glycero-3-phospho)-1D-myo-inositol(out) a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol)(in) = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol)(out) a 1,2-diacyl-sn-glycero-3-phosphocholine(in) = a 1,2-diacyl-sn-glycero-3-phosphocholine(out) a 1,2-diacyl-sn-glycero-3-phosphoethanolamine(in) = a 1,2-diacyl-sn-glycero-3-phosphoethanolamine(out) Ubiquitously expressed. Up-regulated by cisplatin. Belongs to the CLPTM1 family.