Conversion of glycerol 3-phosphate to dihydroxyacetone phosphate. Functional analog of glpA1 required for the basal levels of glycerol-3-phosphate dehydrogenase activity, but not expressed during standard growth on glycerol or when glpA1 is knockout. a quinone + sn-glycerol 3-phosphate = a quinol + dihydroxyacetone phosphate Polyol metabolism; glycerol degradation via glycerol kinase pathway; glycerone phosphate from sn-glycerol 3-phosphate (anaerobic route): step 1/1. Composed of a catalytic GlpA/B dimer and of membrane bound GlpC. No visible phenotype. H.volcanii contains 2 glpABC operons, one located on the main chromosome and the other on megaplasmid pHV4. Belongs to the FAD-dependent glycerol-3-phosphate dehydrogenase family.