The expression of recombinant proteins in Escherichia coli often leads to inactive aggregated proteins known as the inclusion bodies To date, the best available tool has been the use of fusion tags, including the carbohydrate-binding protein, e g, the maltose-binding protein (MBP) that enhances the solubility of recombinant proteins However, none of these fusion tags work universally with every partner protein We hypothesized that galectins, which are also carbohydrate-binding proteins, may help as fusion partners in folding the mammalian proteins in E coli Here we show for the first time that a small soluble lectin, human galectin-1, one member of a large galectin family, can function as a fusion partner to produce soluble folded recombinant human glycosyltransferase, beta-1,4-galactosyltransferase-7 (beta 4Gal-T7), in E coli. The enzyme beta 4Gal-T7 transfers galactose to xylose during the synthesis of the tetrasaccharide linker sequence attached to a Ser residue of proteoglycans Without a fusion partner. beta 4Gal-T7 is expressed in E colt as inclusion bodies We have designed a new vector construct, pLgals1, from pET-23a that includes the sequence for human galectin-1, followed by the Tev protease cleavage site, a 6 x His-coding sequence, and a multi-cloning site where a cloned gene is inserted After lactose affinity column purification of galectin-1-beta 4Gal-T7 fusion protein, the unique protease cleavage site allows the protein beta 4Gal-T7 to be cleaved from galectin-1 that binds and elutes from UDP-agarose column The eluted protein is enzymatically active, and shows CD spectra comparable to the folded beta 4Gal-T1 The engineered galectin-1 vector could prove to be a valuable tool for expressing other proteins in E coli Published by Elsevier Inc