UDP-glycosyltransferases

Mackenzie PI, Owens IS, Burchell B, Bock KW, Bairoch A, Belanger A et al. The UDP glycosyltransferase gene superfamily recommended nomenclature update based on evolutionary divergence. Pharmacogenetics 1997 7[4] 255-269. 

The present review covers a description of methodology and properties of UDP-glucuronyltransferase and of related UDP-glycosyltransferase activities (assayed with bilirubin as the acceptor substrate) and attempts to delineate applications to human disease. Studies with other hydro-phobic acceptor substances will be discussed as far as relevant to the subject matter. 

The general term UDP-glycosyltransferase or the more specific ones UDP-glucuronyl-, UDP-glucosyl-, and UDP-xylosyltransferase will bo employed as convenient. They are used primarily to denote enzyme activities observable in broken cell preparations. This practice does not imply any expression of opinion with regard to the existence of either a single polyfunctional enzyme system, or of several enzymes with different specificities toward the sugar donor (Section 7). 

Obviously, extrapolation procedures are impractical for routine determination of enzyme activities. When substrate saturation-curves conform to rectangular hyperbolas, reasonable concentrations of substrates should equal 10 to 20 times the respective Km values. As outlined above, application of this rule to assays of bilirubin UDP-glycosyltransferase activities is hampered by substrate inhibition and by occasional deviation from Michaelis-Menten kinetics. The best alternative in such cases may be to choose the concentrations at optimal enzyme activity. However, great care should be exercised in interpreting the results. When a bio-... 

Procedures for Determination of Conjugated Bilirubin Applicable to the Assay of Bilirubin UDP-Glycosyltransferase... 

Partial or total deficiency, or inhibition of bilirubin UDP-glucuronyltransferase may cause unconjugated hyperbilirubinemia. Increased production (hemolysis, ineffective erythropoiesis) should be excluded by investigating hematologic parameters. Determination in vitro of bilirubin UDP-glycosyltransferase activities can contribute to a differential diagnosis. To minimize the effect of cytoplasmic carrier proteins, in in vitro... 

Dehydroshikiniate-dehydrogenase 2 Carboxylic add reductase 3 0-Methyltransferase 4 UDP-Glycosyltransferase 5 Alcohol dehydrogenase... 

Malik, V. and Black, G.W. (2012) Stmc-tural, functional, and mutagenesis studies of UDP-glycosyltransferases. 

Woo, H.-H., Orbach, M., Hirsch, A.M. Hawes, M.C. (1999). Meristem-localized inducible expression of a UDP-glycosyltransferase gene is essential for growth and development in pea and alfalfa. Plant Cell, 11,2303-2316. 

Priest, D.M. et al. (2005) The use of abscisic acid anabgues to analyse (he substrate selectivity of UGT71B6, a UDP-glycosyltransferase of Arabidopsis thaliana. FEBS Lett. 579, 4454-4458... 

Woo, H.H. et al. (2007) Modifying expression of closely related UDP-glycosyltransferases from pea saA Arabidopsis results in altered root development and function. Physiol Plant. 130,250-260... 

Studies in choline-deficient animals indicate that the activity of UDP-glycosyltransferases, important for the synthesis of glycoproteins in liver microsomes, are abnormally low. After addition of phosphoryl-choline plus CTP to a suspension of liver microsomes, there is a rapid repletion of UDP-glycosyltransferase activities (Mookerjea, 1971). CDP-choline had a similar effect. These results suggest that the functional status of UDP-glycosyltransferases is altered by manipulation of the compositions of phospholipid headgroups. 

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