Stellacyanin

[1] Stellacyanin’s spectroscopic properties help us differentiate it from plastocyanin, which is another monocopper blue protein found in plants.

The glutamine residue takes place of a methionine ligand typically found in other blue copper proteins.

However, given the fact that type I copper proteins are involved in electron transfer and stellacyanin appears to be associated with the plant cell wall, it is suggested that it is involved in oxidative cross-linking reactions to build polymeric material making up the cell wall.

[1][3] Cell wall structural glycoproteins contain hydroxyproline and serine-rich sequence domains which are found in stellacyanins.

Stellacyanins are most involved in redox reactions of plants that take place during a defense response, and formation of lignin.