Alpha-glycerophosphate oxidase, also known as glycerol-3-phosphate dehydrogenase (GlpD) is an essential membrane enzyme which functions at the central junction of respiration, glycolysis, and phospholipid biosynthesis. Its critical role is indicated by the multitiered regulatory mechanisms that stringently controls its expression and function. Homologs of GlpD are found in practically all organisms, from prokaryotes to humans.

Structural domains comprising this superfamily share the structure of the C-terminal cap domain of alpha-glycerophosphate oxidase which shows an overall negative electrostatic surface, believed to aid in substrate recognition. The positive electrostatic potential of the base of the FAD-domain delineates the regions that interacts with the negative phospholipid head groups of the membrane bilayer. The distinct electrostatic "polarity" of these distal regions are likely involved in the establishment of a proper alignment of GlpD into the membrane bilayer PMID:18296637,PMID:18154320.