The mammalian enzyme is composed of at least six subunits (PIG-A, PIG-H, PIG-C, PIG-P, PIG-Y, and GPI1). PIG-A is the catalytic subunit.
This enzyme belongs to the family of glycosyltransferases, to be specific the hexosyltransferases. The systematic name of this enzyme class is UDP-N-acetyl-D-glucosamine:1-phosphatidyl-1D-myo-inositol 6-(N-acetyl-alpha-D-glucosaminyl)transferase. Other names in common use include UDP-N-acetyl-D-glucosamine:phosphatidylinositol, N-acetyl-D-glucosaminyltransferase, uridine diphosphoacetylglucosamine, and alpha1,6-acetyl-D-glucosaminyltransferase. This enzyme participates in 3 metabolic pathways: glycosylphosphatidylinositol(gpi)-anchor, ???, and glycan structures - biosynthesis 2.
References
Doering TL, Masterson WJ, Englund PT, Hart GW (July 1989). "Biosynthesis of the glycosyl phosphatidylinositol membrane anchor of the trypanosome variant surface glycoprotein. Origin of the non-acetylated glucosamine". The Journal of Biological Chemistry. 264 (19): 11168–73. PMID2525555.