In plant cells, galactolipids are predominant, representing up to 50% of the lipid content in photosynthetic tissues. Galactolipid synthesis is initiated by MGDG synthases (MGDs), which use UDP-galactose as a donor sugar and diacylglycerol (DAG) as acceptor, to form monogalactosyldiacylglycerol (MGDG). This protocol is used to produce a recombinant form of Arabidopsis thaliana (A. thaliana) monogalactosyldiacylglycerol synthase 1 (MGD1) protein, in Escherichia coli (E. coli), using a two-step chromatographic purification procedure. The protein is easily expressed and purified to milligram quantities, suitable for biochemical and structural studies. The crystallization of MGD1 is also described.