Galactosyl transferases of baby hamster kidney (BHK) cells

Publisher Website
Google Scholar
Abstract
Extracts of BHK cells catalyze incorporation of galactose from UDP-galactose into asialo bovine submaxillary gland mucin. The galactosylated oligosaccharide products were released by alkaline-borohydride treatment and purified by Bio-Gel P2 chromatography and high-performance liquid chromatography. The structures of the oligosaccharide sequences sythesized were identified unequivocally by high resolution 500 MHz 1H-NMR as galactosyl-(.beta.1 .fwdarw. 3) N-acetylgalactosamine and galactosyl-(.beta.1 .fwdarw. 4) N-acetylglucosaminyl-(.beta.1 .fwdarw. 3)-N-acetylgalactosamine. Characterization of the latter sequence shows the presence in bovine mucin of the type III core sequence N-acetylglucosamine-(.beta.1 .fwdarw. 3) N-acetylgalactosamine. Fractionation of BHK cell extracts on .alpha.-lactalbumin-Agarose showed that the (.beta.1 .fwdarw. 4)-galactosyl transferase responsible for synthesis of the trisaccharide binds to .alpha.-lactalbumin, a modulator of the (.beta.1 .fwdarw. 4)-galactosyl transferase involved in N-glycan assembly. The evidence that the same transferase activity may be responsible for galactose transfer to both O-glycans and N-glycans is discussed.