Blue (type 1) copper domain (IPR000923)

Short name: BlueCu_1

Overlapping homologous superfamilies

Domain relationships


Blue (type 1) copper proteins constitute a diverse class of proteins, including small blue proteins and multicopper oxidases. They bind copper and are characterised by an intense electronic absorption band near 600 nm [PMID: 6698995, PMID: 8433378].

The most well known members of this class of proteins are the small blue proteins, which includes azurins and plastocyanins. It is a group of monomeric proteins which contain one copper ion per molecule. The plant chloroplastic plastocyanins exchange electrons with cytochrome c6, and the distantly related bacterial azurins exchange electrons with cytochrome c551. This group also includes amicyanin from bacteria such as Methylobacterium extorquens or Paracoccus versutus (Thiobacillus versutus) that can grow on methylamine; auracyanins A and B from Chloroflexus aurantiacus [PMID: 1313011]; blue copper protein from Alcaligenes faecalis; cupredoxin (CPC) from Cucumis sativus (Cucumber) peelings [PMID: 1468551]; cusacyanin (basic blue protein; plantacyanin, CBP) from cucumber; halocyanin from Natronomonas pharaonis (Natronobacterium pharaonis) [PMID: 8195126], a membrane associated copper-binding protein; pseudoazurin from Pseudomonas; rusticyanin from Thiobacillus ferrooxidans [PMID: 1879547]; stellacyanin from Rhus vernicifera (Japanese lacquer tree); umecyanin from the roots of Armoracia rusticana (Horseradish); and allergen Ra3 from ragweed. This pollen protein is evolutionary related to the above proteins, but seems to have lost the ability to bind copper.

The small blue proteins are single-domain proteins. The domain consists of a beta-sheet sandwich, composed of eight strands in two sheets, and has predominantly antiparallel beta-strand topology [PMID: 1995346]. This entry represents the blue copper domain.

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0005507 copper ion binding
GO:0009055 electron transfer activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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