The effect of N-linked glycosylation on the substrate preferences of UDP glucuronosyltransferases

https://doi.org/10.1016/0006-291X(90)91006-EGet rights and content

Abstract

The presence of potential N-linked glycosylation sites (Asn-X-Ser/Thr) in two forms of UDP glucuronosyltransferase, designated UDPGTr-2 and UDPGTr-4, has been deduced from cDNA sequence data. These forms were glycosylated when synthesized from expression vectors transfected into COS cells and were converted to faster migrating species on SDS polyacrylamide gels when treated with endoglycosidase H. The role of glycosylation was investigated by determining the substrate specificities and stabilities of the glycosylated enzymes and their unglycosylated variants which were synthesized in the presence of tunicamycin. Analysis of the activities towards 13 different aglycones showed that the glycosyl moiety was not essential for catalytic activity and had no effect on the substrate preference of each form. The stabilities of the proteins were not adversely affected by the absence of this posttranslational modification. A possible effect of N-linked oligosaccharides on the catalytic properties of these two forms of UDP glucuronosyltransferase is discussed.

References (17)

  • BurchellB. et al.

    Molec. Aspects Med.

    (1987)
  • SiestG. et al.

    Biochem. Pharmacol.

    (1987)
  • MackenzieP.I.

    J. Biol. Chem.

    (1987)
  • MackenzieP.I.

    J. Biol. Chem.

    (1986)
  • IyanagiT. et al.

    J. Biol. Chem.

    (1986)
  • GibsonR. et al.

    Trends Biol. Sci.

    (1980)
  • ElbeinA.D.

    Trends Biochem. Sci.

    (1981)
  • MackenzieP.I.

    J. Biol. Chem.

    (1986)
There are more references available in the full text version of this article.

Cited by (24)

  • The UGTome: The expanding diversity of UDP glycosyltransferases and its impact on small molecule metabolism

    2019, Pharmacology and Therapeutics
    Citation Excerpt :

    Subsequently, endoglycosidase H digestions of purified and recombinant proteins demonstrated the presence of oligosaccharide chains attached to asparagine residues in UGT proteins (Green & Tephly, 1989; Mackenzie, 1990). The glycan chain was not essential for catalytic activity and appeared not to alter the substrate preferences of each UGT (Mackenzie, 1990). However, it may be important for correct folding and maintenance of fully-active enzymes, as described for UGT1A9 (Nakajima et al., 2010) and UGT2B7 (Girard-Bock, Benoit-Biancamano, Villeneuve, Desjardins, & Guillemette, 2016).

  • Characterization of human UGT2A3 expression using a prepared specific antibody against UGT2A3

    2019, Drug Metabolism and Pharmacokinetics
    Citation Excerpt :

    UGTs are membrane-bound enzymes associated with post-translational modifications through the ER. Some UGT isoforms are N-linked glycosylated on the ER membrane [26–30]. As shown in Fig. 2A, UGT2A3 also contains potential N-glycosylation sites.

  • Hepatic Drug Metabolism in Pediatric Patients

    2017, Drug Metabolism in Diseases
  • N-Glycosylation plays a role in protein folding of human UGT1A9

    2010, Biochemical Pharmacology
    Citation Excerpt :

    As for UGTs, it has been demonstrated that deglycosylation of the purified rabbit UGT1A6, UGT2B13, rat UGT1A6 and UGT2B2 proteins by endoglycosidase H (Endo H) did not decrease their enzyme activities [10]. Mackenzie [9] has reported that rat UGT2B1 and UGT2B2 are N-glycosylated and the treatment of COS cells expressing these UGTs with tunicamycin, which inhibits the first step of N-glycosylation, i.e., translocation of oligosaccharide core units to peptides, resulted in the production of less active enzymes. However, the unglycosylated proteins showed similar substrate specificity and protein stability as the native proteins.

View all citing articles on Scopus
View full text