Extensins are a family of flexuous, rodlike, hydroxyproline-rich glycoproteins (HRGPs) of the plant cell wall.
Typically they have two major diagnostic repetitive peptide motifs, one hydrophilic and the other hydrophobic, with potential for crosslinking.
Extensins are thought to act as self-assembling amphiphiles[3] essential for cell-wall assembly and growth by cell extension and expansion.
Polypeptides targeted for secretion are subsequently hydroxylated by direct addition of molecular oxygen to proline at C-4.
[4] Extensin hydroxyproline is uniquely glycosylated with short chains of L-arabinose[8] that further rigidify[9] and increase hydrophilicity.