Glyceraldehyde-3-P dehydrogenases (GAPDH s) are enzymes conserved in all living organisms, where they play a centr al role in the carbon econ omy of the cells.Higher plan ts posses s four distin ct isofor ms of GAPDH s: (1) GAPC, a cytoso lic, pho sphoryl ating,NAD-sp ecific GAPDH catalyzi ng the co nversion of glyceral dehyde -3-P (Ga3P) to 1,3-bisp hosphog lycer-ate; (2) NP-GAPD H, a cyto solic non-p hosp horylatin g NADP- dependen t GAPDH that catalyze s the oxida-tion of Ga3P to 3-phosp hoglyce rate (3PGA ; Valverde et al., 2005); (3) GAPA/B, a pho sphoryl ating, NADP-specific GAPDH involv ed in photo synthetic CO2 fix-ation in chloroplasts (Cerff and Chambe rs, 1979); and(4) GA PCp, invo lved in glycoly tic energy production in non- green plastids (Pe tersen et al., 2003).