Involved in the plastidial phosphorylated pathway of serine biosynthesis (PPSB). (2R)-3-phosphoglycerate + NAD(+) = 3-phosphooxypyruvate + H(+) + NADH Inhibited by 90 uM 3-phosphonooxypyruvate, but not by Ser, Thr, Val, Gly Trp, O-acetyl-L-Ser and Cys. Amino-acid biosynthesis; L-serine biosynthesis; L-serine from 3-phospho-D-glycerate: step 1/3. Ubiquitous, but highly expressed in roots and in dark-grown leaf tissues. Expressed in the vasculature, stigma, anther filaments and shoot apical meristem. Not detected in the root meristem or in embryo. Not regulated by high CO(2) levels. Up-regulated upon necrotrophic pathogen infection. No visible phenotype. Belongs to the D-isomer specific 2-hydroxyacid dehydrogenase family.