PIG-H is a family of conserved proteins that complexes with three other proteins to form the GPI-GnT (glycosylphosphatidylinositol anchor biosynthesis transferase) complex. It appears to be a peripheral membrane protein facing the cytoplasm involved in the first step in GPI anchor formation.

1: The first step of glycosylphosphatidylinositol biosynthesis is mediated by a complex of PIG-A, PIG-H, PIG-C and GPI1. Watanabe R, Inoue N, Westfall B, Taron CH, Orlean P, Takeda J, Kinoshita T; EMBO J. 1998;17:877-885. PMID:9463366