The plant cell wall protein O-glycome – University of Copenhagen

The plant cell wall protein O-glycome

Extensins and arabinogalactanproteins (AGPs) are O-glycosylated hydroxyproline (Hyp)-rich glycoproteins (HRGPs), which provide structural integrity to the cell wall, control extension growth and mediate cell-cell interactions and communication. The AGP- and extensin peptide backbone feature non-contiguous and contiguous Hyp residues, carrying the AG-glycan or short arabinosides (see fig), respectively.

Synthesis of the glycans is carried out by a battery of glycosyltransferases (GTs) and takes place during passage of the HRGP through the ER and the Golgi apparatus, before the mature glycoprotein is inserted into the cell wall or secreted from the cell. 

We have identified a hand full of GTs, which are involved in extensin-  (, and AGP synthesis ( Using forward and reverse genetics, we are now working on assigning specific biochemical function to particular GTs.

All key arabinosyltransferase activities (ArafTs), except for the innermost backbone activity, involved in extensin glycan synthesis have now been identified or characterized in our lab:



Extensins are considered primordial to higher plant complex glycan polymer based cell wall and extensin type HRGPs may thus prove significant for second generation plant and algal derived biofuels. Extensin type glycans is also involved in hormone signaling and implicated in Group I grass pollen- and perhaps food allergenicity and recent research imply that introduction of AGP and perhaps extensin type of glycans may improve yields and pharmaceutical properties cell factories producing protein pharma ceuticals. 

Selected publications:

  • Velasquez SM, Ricardi MM, Dorosz JG, Fernandez PV, Nadra AD, Pol-Fachin L, Egelund J, Harholdt J, Gille S, Ciancia M, Verli H, Pauly M, Bacic A, Olsen CE, Ulvskov P, Petersen BL, Somerville C, Iusem ND, Estevez JM (2011) Essential role of O-glycosylated cell wall proteins in polarized root hair growth. Science, In press.
  • Petersen et al. (2007) Da planterne gik på land – Cellevæggens opbygning og funktion.