Purification, properties and possible gene assignment of an ?1,3-fucosyltransferase expressed in human liver

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Abstract
α1,3-Fucosyltransferase solubilized from human liver has been purified 40 000-fold to apparent homogeneity by a multistage process involving cation exchange chromatography on CM-Sephadex, hydrophobic interaction chromatography on Phenyl Sepharose, affinity chromatography on GDP-hexanolamine Sepharose and HPLC gel exclusion chromatography. The final step gave a major protein peak that co-chromatographed with α1,3-fucosyltransferase activity and had a specific activity of ∼ 5–6 µmol min−1 mg−1 and anM r ∼ 44 000 deduced from SDS-PAGE and HPLC analysis. The purified enzyme readily utilized Galβ1-4GlcNAc, NeuAcα2-3Galβ1-4GlcNAc and Fucα1-2Galβ1-4GlcNAc, with a preference for sialylated and fucosylated Type 2 acceptors. Fucα1-2Galβ1-4Glc and the Type 1 compound Galβ1-3GlcNAc were very poor acceptors and no incorporation was observed with NeuAcα2-6Galβ1-4GlcNAc. A polyclonal antibody raised against the liver preparation reacted with the homologous enzyme and also with the blood group Lewis gene-associated α1,3/1,4-fucosyltransferase purified from the human A431 epidermoid carcinoma cell line. No cross reactivity was found with α1,3-fucosyltransferase(s) isolated from myeloid cells. Examination by Northern blot analysis of mRNA from normal liver and from the HepG2 cell line, together with a comparison of the specificity pattern of the purified enzyme with that reported for the enzyme expressed in mammalian cells transfected with theFuc-TVI cDNA, suggests a provisional identification ofFuc-TVI as the major α1,3-fucosyltransferase gene expressed in human liver.