Impact of glycosylation and detergent-resistant membranes on the function of intestinal sucrase-isomaltase.
Sucrase-isomaltase (SI) is a highly N- and O-glycosylated intestinal brush border membrane protein. SI is sorted with high fidelity to the apical membrane via O-linked glycans that mediate its association with lipid rafts or detergent-resistant membranes (DRMs). Here, we show that N- and O-glycosylation and DRMs are implicated in the regulation of the function of SI in intestinal Caco-2 cells. The activities of sucrase (SUC) and isomaltase (IM) increase substantially in DRMs when N- and O-glycosylation patterns are intact. Disruption of DRMs by solubilization with Triton X-100 at 37 degrees C substantially reduces the activities of SUC and IM. Furthermore, modulation of O-glycosylation by benzyl-2-acetamido-2-deoxy-alpha-d-galactopyranoside and N-glycosylation by deoxymannojirimycin is linked to a decreased capacity of SI to associate with DRMs, with a subsequent reduction of the enzymatic activities of SUC and IM. This is the first report that reveals a direct role of N- and O-glycans in association with DRMs in regulating the function of a membrane glycoprotein.
Department of Physiological Chemistry, University of Veterinary Medicine Hannover, D-30559 Hannover, Germany.
Gabi
G
Wetzel
Martin
M
Heine
Arndt
A
Rohwedder
Hassan Y
HY
Naim
D017485:1-Deoxynojirimycin / Q000494:pharmacology; D000116:Acetylgalactosamine / Q000031:analogs & derivatives / Q000494:pharmacology; D001593:Benzyl Compounds / Q000494:pharmacology; D018938:Caco-2 Cells; D002462:Cell Membrane / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D003902:Detergents / Q000494:pharmacology*; D006031:Glycosylation / Q000187:drug effects; D006801:Humans; D007422:Intestines / Q000166:cytology* / Q000201:enzymology*; D008871:Microvilli / Q000201:enzymology; D013394:Sucrase-Isomaltase Complex / Q000378:metabolism*
D001593:Benzyl Compounds; D003902:Detergents; D017485:1-Deoxynojirimycin; C080739:benzyl-alpha-N-acetylgalactosamine; D013394:Sucrase-Isomaltase Complex; D000116:Acetylgalactosamine