Ethanolaminephosphotransferase 1 (SELENOI)

Ethanolaminephosphotransferase 1 (SELENOI) is a unique multi-pass endoplasmic reticulum (ER) transmembrane enzyme that contains a selenocysteine (Sec) residue and belongs to both the selenoprotein and lipid phosphotransferase protein families[1][3][5]. SELENOI exclusively catalyzes the transfer of phosphoethanolamine from CDP-ethanolamine to diacylglycerol (DAG) or 1-alkyl-2-acylglycerol (AAG), resulting in the synthesis of phosphatidylethanolamine (PE) and plasmanyl PE—key steps in the Kennedy pathway central to cell membrane formation and function[1][2][4][5]. This function is not a redox reaction and, unlike most selenoproteins, SELENOI’s selenocysteine is not directly involved in its catalytic activity[1][2]. Deficiency or mutation in SELENOI leads to impaired synthesis of PE and plasmalogens, fundamentally affecting CNS development and function and causing rare neurodegenerative disorders like hereditary spastic paraplegia[1][2]. SELENOI plays a critical metabolic role in cell types with high membrane synthesis demands, such as proliferating immune cells, and is essential for viability in mammals[1][2][3][5].

Other names

Selenoprotein ISELENOIEPT1KIAA1724SELIhEPT1SEPISPG81ethanolaminephosphotransferase 1 (CDP-ethanolamine-specific)