Extensins are abundant wall glycoprotein and are the best characterized structural protein. For comprehensive reviews readers should consult Showalter(1993) ; Cassab(1998); Lamport(2001) and references therein . In general, extension genes encode proteins with a signal peptide followed by a repetitive region rich in Pro/Hyp, with the main repeat motif being SP4. They are rich in Hyp and Ser, and moderately abundant in val, Tyr, Lys and His. Extensins are basic proteins with isoelectric points of 10 due to the Lys content.