Phosphatidylinositolglycan class N (PIG-N) is a mammalian homologue of the yeast protein MCD4P and is expressed in the endoplasmic reticulum [1]. PIG-N is essential for glycosylphosphatidylinositol anchor synthesis. Glycosylphosphatidylinositol (GPI)-anchored proteins are cell surface-localised proteins that serve many important cellular functions [2].

1: Pig-n, a mammalian homologue of yeast Mcd4p, is involved in transferring phosphoethanolamine to the first mannose of the glycosylphosphatidylinositol. Hong Y, Maeda Y, Watanabe R, Ohishi K, Mishkind M, Riezman H, Kinoshita T; J Biol Chem 1999;274:35099-35106. PMID:10574991

2: MCD4 encodes a conserved endoplasmic reticulum membrane protein essential for glycosylphosphatidylinositol anchor synthesis in yeast. Gaynor EC, Mondesert G, Grimme SJ, Reed SI, Orlean P, Emr SD; Mol Biol Cell 1999;10:627-648. PMID:10069808