Plays a role in regulating cardiac sodium current; decreased enzymatic activity with resulting increased levels of glycerol 3-phosphate activating the DPD1L-dependent SCN5A phosphorylation pathway, may ultimately lead to decreased sodium current; cardiac sodium current may also be reduced due to alterations of NAD(H) balance induced by DPD1L. NAD(+) + sn-glycerol 3-phosphate = dihydroxyacetone phosphate + H(+) + NADH Interacts with SCN5A. Belongs to the NAD-dependent glycerol-3-phosphate dehydrogenase family. Extended N-terminus. Extended N-terminus.