Effects of endogenous soluble beta-galactoside binding lectins and protein inhibitor of fucosyltransferase on the enzymes involved in the intestinal fucosylation process.
Soluble beta-galactoside binding lectins were prepared from the rat small intestinal mucosa by chromatography on asialofetuin-Sepharose. The lectin fraction exhibits 3 bands with Mr of 21,5 kDa, 19 kDa and 17 kDa on SDS-PAGE. This fraction inhibits a partially purified soluble alpha(1-2)-fucosyltransferase by interaction with the glycoprotein substrate asialofetuin, whereas the inhibition is non competitive for the donor GDP-fucose. It has no effect on other enzymes of the fucosylation system, namely glycosyl-nucleotide pyrophosphatase and the system synthesizing GDP-fucose from GDP-mannose. A different and specific soluble protein inhibitor of fucosyltransferase activity inhibits this activity by a competitive mechanism for GDP-fucose and a non competitive one for asialofetuin. Unlike the lectins, this inhibitor also inhibits the action of pyrophosphatase and the formation of GDP-fucose by different mechanisms. The possible extension of these in vitro results to the in vivo regulation of glycosylation is discussed.
Ruggiero-Lopez
D
D
Département de Biochimie Générale et Médicale, INSERM 189 alliée au CNRS, Faculté de Médecine Lyon-Sud, Oullins, France.
Louisot
P
P
Martin
A
A
D000818:Animals; D005647:Fucosyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005697:Galactosides / Q000378:metabolism; D006154:Guanosine Diphosphate Fucose / Q000378:metabolism; D007413:Intestinal Mucosa / Q000201:enzymology*; D007700:Kinetics; D037102:Lectins / Q000378:metabolism*; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains
D005697:Galactosides; D037102:Lectins; D006154:Guanosine Diphosphate Fucose; D005647:Fucosyltransferases