PROSITE documentation PDOC51485
Phytocyanin domain profile


Among the blue copper proteins with a single type I (or "blue") mononuclear copper site, the plant-specific phytocyanins constitute a distinct subfamily that can be further subdivided into the families of uclacyanins, stellacyanins, plantacyanins, and early nodulins. Stellacyanins have a blue copper coordinated 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 [1,2,3,4]. Early nodulins lack amino acid residues that coordinate Cu, so they are believed to be involved in unknown processes without binding Cu [5]. Phytocyanins are found in chloropasts of higher plants.

The phytocyanin domain has a core of seven polypeptide strands arranged as a β-sandwich comprising two β-sheets, β-sheet I and β-sheet II (see <PDB:1WS8>). β-sheet I consists of three β-strands and β-sheet II consists of four β-strands. A disulfide bridge close the metal center is characteristic for phytocyanins, in contrast to azurins, pseudoazurins, and plastocyanins, where a disulfide bond is located on the distal side of the β-barrel. This disuldide bridge may play a crucial role in maintaining the tertiary structure of the protein and/or the formation of the copper binding center because one of the His ligands of copper is followed directly by a bridging Cys residue [1,2,3,,4].

Some proteins known to contain a phytocyanin domain are listed below:

  • Cucumber basic protein (CBP).
  • Spinach basic protein (SBP).
  • Cucumber stellacyanin (CST).
  • Zucchini mavicyanin.

The profile we developed covers the entire phytocyanin domain.

Last update:

April 2010 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

PHYTOCYANIN, PS51485; Phytocyanin domain profile  (MATRIX)


1AuthorsNersissian A.M. Immoos C. Hill M.G. Hart P.J. Williams G. Herrmann R.G. Valentine J.S.
TitleUclacyanins, stellacyanins, and plantacyanins are distinct subfamilies of phytocyanins: plant-specific mononuclear blue copper proteins.
SourceProtein Sci. 7:1915-1929(1998).
PubMed ID9761472

2AuthorsEinsle O. Mehrabian Z. Nalbandyan R. Messerschmidt A.
TitleCrystal structure of plantacyanin, a basic blue cupredoxin from spinach.
SourceJ. Biol. Inorg. Chem. 5:666-672(2000).
PubMed ID11085657

3AuthorsXie Y. Inoue T. Miyamoto Y. Matsumura H. Kataoka K. Yamaguchi K. Nojini M. Suzuki S. Kai Y.
TitleStructural reorganization of the copper binding site involving Thr15 of mavicyanin from Cucurbita pepo medullosa (zucchini) upon reduction.
SourceJ. Biochem. 137:455-461(2005).
PubMed ID15858169

4AuthorsKoch M. Velarde M. Harrison M.D. Echt S. Fischer M. Messerschmidt A. Dennison C.
TitleCrystal structures of oxidized and reduced stellacyanin from horseradish roots.
SourceJ. Am. Chem. Soc. 127:158-166(2005).
PubMed ID15631465

5AuthorsMashiguchi K. Asami T. Suzuki Y.
TitleGenome-wide identification, structure and expression studies, and mutant collection of 22 early nodulin-like protein genes in Arabidopsis.
SourceBiosci. Biotechnol. Biochem. 73:2452-2459(2009).
PubMed ID19897921

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