In the three domains of life, lipid-linked glycans contribute to various cellular processes ranging from protein glycosylation to glycosylphosphatidylinositol anchor biosynthesis to peptidoglycan assembly. In generating many of these glycoconjugates, phosphorylated polyprenol-based lipids are charged with single sugars by polyprenol phosphate glycosyltransferases. The resultant substrates serve as glycosyltransferase donors, complementing the more common nucleoside diphosphate sugars. It had been accepted that these polyprenol phosphate glycosyltransferases acted similarly, given their considerable sequence homology. Recent findings, however, suggest that matters may not be so simple. In this Opinion we propose that the stereochemistry of sugar addition by polyprenol phosphate glycosyltransferases is not conserved across evolution, even though the GT-A fold that characterizes such enzymes is omnipresent.

在生命的三个领域中，脂质连接的聚糖参与了各种细胞过程，从蛋白质糖基化到糖基磷脂酰肌醇锚定生物合成到肽聚糖装配。在产生许多这些糖缀合物中，磷酸化的基于聚戊二烯的脂质通过聚戊二烯磷酸糖基转移酶被单糖所带。所得的底物用作糖基转移酶供体，补充了更常见的核苷二磷酸糖。鉴于它们的相当的序列同源性，这些聚戊二烯磷酸糖基转移酶的作用相似，已经被接受。然而，最近的发现表明事情可能不是那么简单。在本意见中，我们建议在整个进化过程中不保守通过聚戊二烯磷酸酯糖基转移酶添加糖的立体化学，