Catalyzes the NAD(P)H-dependent reduction of dihydroxyacetonephosphate (DHAP or glycerone phosphate) to glycerol 1-phosphate (G1P). The G1P thus generated is probably used for the synthesis of phosphoglycerolipids in Gram-positive bacterial species. Prefers NADH over NADPH as coenzyme. Is also able to catalyze the reverse reaction, i.e. the NAD(+)-dependent oxidation of G1P but not of G3P. Does not possess glycerol dehydrogenase activity. NAD(+) + sn-glycerol 1-phosphate = dihydroxyacetone phosphate + H(+) + NADH NADP(+) + sn-glycerol 1-phosphate = dihydroxyacetone phosphate + H(+) + NADPH Binds 1 nickel ion per subunit. Is not active with other divalent metal cations such as Zn(2+), Cu(2+), Ca(2+), Mg(2+), Mn(2+) or Fe(2+). Optimum pH is 8.2. Homodimer. Transcription is repressed by glucose and by the binding of AraR to the operon promoter. L-arabinose acts as an inducer by inhibiting the binding of AraR to the DNA, thus allowing expression of the gene. Belongs to the glycerol-1-phosphate dehydrogenase family.