Phosphatidylinositol glycan anchor biosynthesis class G protein (PIGG)

Phosphatidylinositol glycan anchor biosynthesis class G protein (PIGG) is an endoplasmic reticulum (ER)-localized enzyme that functions as the catalytic subunit of the ethanolamine phosphate transferase 2 complex[5][1]. PIGG transfers an ethanolamine phosphate group from phosphatidylethanolamine to the second mannose residue during biosynthesis of glycosylphosphatidylinositol (GPI) anchors, which attach certain proteins to the cell surface[5][1][3]. Over 150 proteins require GPI anchors for membrane localization and function, impacting a wide range of developmental and physiological processes, particularly in the nervous system[3][1]. Pathogenic variants in PIGG cause inherited GPI deficiency, resulting in neurodevelopmental disorders characterized by intellectual disability, hypotonia, early-onset seizures, cerebellar atrophy, and (in some cases) mitochondrial dysfunction[1][3]. Fibroblasts from patients often show reduced levels of specific GPI-anchored proteins, especially CD73, providing a functional biomarker[3]. Currently, no drugs are documented for direct modulation of PIGG activity, and owing to its fundamental role in cell biology, it is a potential but high-risk therapeutic target[5][3][1].

Other names

GPI ethanolamine phosphate transferase 2, catalytic subunitGPI7hGPI7PIG-GFLJ20265LAS21MRT53NEDHSCAPRO4405RLGS1930EMM blood group antigenGPI7 homologLAS21 (GPI7) homolog (S. cerevisiae)EMM