Occurrence of poly-N-acetyllactosamine synthesis in Sf-9 cells upon transfection of individual human beta-1,4-galactosyltransferase I, II, III, IV, Vand VI cDNAs

Lectin blot analysis of membrane glycoprotein samples from Sf-9 cells upon transfection of individual human beta -1,4-galactosyltransferase (beta -1,4 -GalT) I, II, III, IV, V et VI cDNAs showed that the endogenous N-linked ol igosaccharides are galactosylated (Guo et al., Glycobiology (2001), in pres s). Further analysis revealed that membrane glycoprotein samples from all t he gene-transfected cells are also reactive to Lycopersicon esculentum aggl utinin (LEA) et Datura stramonium agglutinin (DSA), both of which bind to o ligosaccharides with poly-N-acetyllactosamine chains while no lectin reacti ve protein bands are detected when blots are pretreated with a mixture of d iplococcal beta -1,4-galactosidase et jack bean beta -N-acetylhexosaminidas e or N-glycanase. Analysis of endo-beta -galactosidase-digestion products r evealed the presence of the Gall --> GlcNAcl --> Gal and/or GlcNAcl --> Gal structures in the gene-transfected cells. When the homogenates of the gene -transfected cells were used as enzyme sources towards oligosaccharides wit h the GlcNAcP1 --> (3Gal beta1 --> 4GlcNAc)(1-3) structures, human recombin ant beta -1,4-GalTs I et II galactosylated these oligosaccharides more effe ctively than other beta -1,4-GalTs. These results indicate that beta -1,4-G alTs I-VI can synthesize poly-N-acetyllactosamine chains with beta -1,3-N-a cetylglucosaminyltransferase. (C) 2001 Societe francaise de biochimie et bi ologie moleculaire/Editions scientifiques et medicales Elsevier SAS. All ri ghts reserved.