Homologous Superfamily

Cupredoxin (IPR008972)

Short name: Cupredoxin

Overlapping entries



Copper is one of the most prevalent transition metals in living organisms and its biological function is intimately related to its redox properties. Since free copper is toxic, even at very low concentrations, its homeostasis in living organisms is tightly controlled by subtle molecular mechanisms. In eukaryotes, before being transported inside the cell via the high-affinity copper transporters of the CTR family, the copper (II) ion is reduced to copper (I). In blue copper proteins such as Cupredoxin, the copper (I) ion form is stabilised by a constrained His2Cys coordination environment.

This entry represents cupredoxin proteins, as well as structural homologues to cupredoxin. Structurally, the cupredoxin-like fold consists of a beta-sandwich with 7 strands in 2 beta-sheets, which is arranged in a Greek-key beta-barrel [PMID: 11867755]. Some of these proteins have lost the ability to bind copper. Proteins with a cupredoxin-type fold are found in the following family groups:

  • Mono-domain cupredoxins, such as amicyanin, plastocyanin, pseudoazurin, plantacyanin, azurin, auracyanin, rusticyanin, stellacyanin, and mavicyanin.
  • Multi-domain cupredoxins, such as nitrite reductase (2 domains of this fold), multicopper oxidase CueO, spore coat protein A, ascorbate oxidase (3 domains of this fold), laccase (3 domains of this fold), ceruloplamin (6 domains of this fold), and coagulation factor V.
  • Red copper protein nitrocyanin and the C-terminal of nitrous oxide reductase.
  • Quinol oxidase and the periplasmic domain of cytochrome c oxidase subunit II.
  • Ephrin-a5 and ephrin-b2 ectodomain, which are related to cupredoxins but lack the metal-binding site.
  • The N-terminal domain of protein arginine deiminase Pad4, which is related to cupredoxin but lacks the metal-biding site.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.