Photosynthetic cells require fructose-1,6-bisphosphatase (FBPase) (EC 3.1.3.11) activity in the chloroplast as well as in the cytoplasm [ 1,11 ]. In both cases the enzyme catalyzes the hydrolysis of fructose-l,6-bisphosphate (F1,6P2) to fructose-6-phosphate (F6P) and inorganic phosphate (Pi). The chloroplast FBPase is an essential enzyme in the photosynthetic pathway of CO2 fixation into sugars. The cytosolic FBPase is required for the synthesis of sucrose from triosephosphate, the major form of reduced carbon exported from the chloroplast during photosynthesis. Due to the importance of the cytosolic FBPase in sucrose biosynthesis in photosynthetic tissues and in gluconeogenesis in non-photosynthetic tissues, a great effort has been focused on understanding the regulatory mechanism of the enzyme Ireviewed in 20, 21]. Nevertheless, most biochemical information, like reactive sites, came from animal systems [7-10, 14, 24]. In this paper, we report the first DNA sequence of a plant cytosolic FBPase. We have isolated and characterized a cDNA encoding a cytosolic FBPase from spinach, compared the amino acid sequence derived from the nucleotide sequence with other published