PROSITE documentation PDOC00174
Type-1 copper (blue) proteins signature


Blue or 'type-1' copper proteins are small proteins which bind a single copper atom and which are characterized by an intense electronic absorption band near 600 nm [1,2]. The most well known members of this class of proteins are the plant chloroplastic plastocyanins, which exchange electrons with cytochrome c6, and the distantly related bacterial azurins, which exchange electrons with cytochrome c551. This family of proteins also includes all the proteins listed below (references are only provided for recently determined sequences).

  • Amicyanin from bacteria such as Methylobacterium extorquens or Thiobacillus versutus that can grow on methylamine. Amicyanin appears to be an electron receptor for methylamine dehydrogenase.
  • Auracyanins A and B from Chloroflexus aurantiacus [3]. These proteins can donate electrons to cytochrome c-554.
  • Blue copper protein from Alcaligenes faecalis.
  • Cupredoxin (CPC) from cucumber peelings [4].
  • Cusacyanin (basic blue protein; plantacyanin, CBP) from cucumber.
  • Halocyanin from Natrobacterium pharaonis [5], a membrane associated copper- binding protein.
  • Pseudoazurin from Pseudomonas.
  • Rusticyanin from Thiobacillus ferrooxidans. Rusticyanin is an electron carrier from cytochrome c-552 to the a-type oxidase [6].
  • Stellacyanin from the Japanese lacquer tree.
  • Umecyanin from horseradish roots.
  • Allergen Ra3 from ragweed. This pollen protein is evolutionary related to the above proteins, but seems to have lost the ability to bind copper.

Although there is an appreciable amount of divergence in the sequence of all these proteins, the copper ligand sites are conserved and we have developed a pattern which includes two of the ligands: a cysteine and a histidine.


In position 5 of the pattern, only the Alcaligenes protein has a Val; all other proteins have either Phe or Tyr. In position 9 only CPC has Gly, all others have Pro.

Last update:

December 2004 / Pattern and text revised.


Technical section

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

COPPER_BLUE, PS00196; Type-1 copper (blue) proteins signature  (PATTERN)


1AuthorsGarret T.P.J. Clingeleffer D.J. Guss J.M. Rogers S.J. Freeman H.C.
SourceJ. Biol. Chem. 259:2822-2825(1984).

2AuthorsRyden L.G. Hunt L.T.
TitleEvolution of protein complexity: the blue copper-containing oxidases and related proteins.
SourceJ. Mol. Evol. 36:41-66(1993).
PubMed ID8433378

3AuthorsMcManus J.D. Brune D.C. Han J. Sanders-Loehr J. Meyer T.E. Cusanovich M.A. Tollin G. Blankenship R.E.
TitleIsolation, characterization, and amino acid sequences of auracyanins, blue copper proteins from the green photosynthetic bacterium Chloroflexus aurantiacus.
SourceJ. Biol. Chem. 267:6531-6540(1992).
PubMed ID1313011

4AuthorsMann K. Schafer W. Thoenes U. Messerschmidt A. Mehrabian Z. Nalbandyan R.
TitleThe amino acid sequence of a type I copper protein with an unusual serine-and hydroxyproline-rich C-terminal domain isolated from cucumber peelings.
SourceFEBS Lett. 314:220-223(1992).
PubMed ID1468551

5AuthorsMattar S. Scharf B. Kent S.B.H. Rodewald K. Oesterhelt D. Engelhard M.
TitleThe primary structure of halocyanin, an archaeal blue copper protein, predicts a lipid anchor for membrane fixation.
SourceJ. Biol. Chem. 269:14939-14945(1994).
PubMed ID8195126

6AuthorsYano T. Fukumori Y. Yamanaka T.
TitleThe amino acid sequence of rusticyanin isolated from Thiobacillus ferrooxidans.
SourceFEBS Lett. 288:159-162(1991).
PubMed ID1879547

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