Extensin

Extensins are a family of flexuous, rodlike, hydroxyproline-rich glycoproteins (HRGPs) of the plant cell wall, discovered by Derek T.A. Lamport at the University of Cambridge.

They are highly abundant proteins. There are around 20 extensins in Arabidopsis thaliana. They form crosslinked networks in the young 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 essential for cell-wall assembly and growth by cell extension and expansion. The name "extensin" encapsulates the hypothesis that they are involved in cell extension.