AUTHOR=Velasquez Silvia M., Salgado Salter Juan , Petersen Bent Larsen , Estevez Jose M. TITLE=Recent Advances on the Posttranslational Modifications of EXTs and Their Roles in Plant Cell Walls JOURNAL=Frontiers in Plant Science VOLUME=3 YEAR=2012 URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2012.00093 DOI=10.3389/fpls.2012.00093 ISSN=1664-462X ABSTRACT=

The genetic set up and the enzymes that define the O-glycosylation sites and transfer the activated sugars to cell wall glycoprotein Extensins (EXTs) have remained unknown for a long time. We are now beginning to see the emerging components of the molecular machinery that assembles these complex O-glycoproteins on the plant cell wall. Genes conferring the posttranslational modifications, i.e., proline hydroxylation and subsequent O-glycosylation, of the EXTs have been recently identified. In this review we summarize the enzymes that define the O-glycosylation sites on the O-glycoproteins, i.e., the prolyl 4-hydroxylases (P4Hs), the glycosyltransferases that transfer arabinose units (named arabinosyltransferases, AraTs), and the one responsible for transferring a single galactose (galactosyltransferase, GalT) on the protein EXT backbones. We discuss the effects of posttranslational modifications on the structure and function of extensins in plant cell walls.