| Type: | Domain | Name: | Phytocyanin domain |
| Description: | Among the blue copper proteins with a single type I (or "blue") mononuclear copper site, the plant-specific phytocyanins constitute a distinct subfamilythat can be further subdivided into the families of uclacyanins, stellacyanins, plantacyanins, and early nodulins. Stellacyanins have a blue coppercoordinated by two His, one Cys and one Gln. In plantacyanins and uclacyanins, the ligands of the type-I Cu sites are two His, one Cys and one Met [, , , ]. Early nodulins lack amino acid residues that coordinate Cu, so they are believed to be involved in unknown processes without binding Cu []. Phytocyanins are found in chloropasts of higher plants.The phytocyanin domain has a core of seven polypeptide strands arranged as a beta-sandwich comprising two beta-sheets, beta-sheet I and beta-sheet II. Beta-sheet I consists of three beta-strands and beta-sheet IIconsists of four beta-strands. A disulfide bridge close the metal centre is characteristic for phytocyanins, in contrast to azurins, pseudoazurins, andplastocyanins, where a disulfide bond is located on the distal side of the beta-barrel. This disuldide bridge may play a crucial role in maintaining thetertiary structure of the protein and/or the formation of the copper binding centre because one of the His ligands of copper is followed directly by abridging Cys residue [, , , ]. Some members of this family (P93328) may not bind copper due to the lack of key residues. Some proteins known to contain a phytocyanin domain are listed below:Cucumber basic protein (CBP).Spinach basic protein (SBP).Cucumber stellacyanin (CST).Zucchini mavicyanin.Some of the proteins in this family are allergens. The allergens in this family include allergens with the following designations: Amb a 3. | Short Name: | Phytocyanin_dom |
