Plastocyanin is a type I copper protein and functions in the electron transfer from PSII to PSI; Plastocyanin is a small copper-containing protein found in cyanobacteria, higher plants, and some algae, where it plays a role in photosynthesis. The two photosystems that are primarily responsible for photosynthesis are photosystem I (PSI) and photosystem II (PSII). The flow of electrons begins in PSII, which acts as a proton pump. Plastocyanin is responsible for transporting electrons from PSII to PSI.

                       10        20        30        40        50        60        70        80
               ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A       5 IKMGADNGMLAFEPSTIEIQAGDTVQWVNNKLAPHNVVVEGQP--------ELSHKDLAFSPGETFEATFSEPGTYTYYC 76
Cdd:cd04219  3 VKMGSDSGALVFEPKELTVKAGDTVEFVNNKGGPHNVVFDEDAvpsavdaaALSHKDLLNAPGETFSVTFPAPGTYTFYC 82

                       90
               ....*....|....*
1BXU_A      77 EPHRGAGMVGKIVVQ 91
Cdd:cd04219 83 EPHRGAGMVGKITVQ 97

Plastocyanin [Energy production and conversion];

                       10        20        30        40        50        60        70
               ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
1BXU_A      14 LAFEPSTIEIQAGDTVQWVNNKLAPHNVVVEGQPELSHKDLAFSPGETFEATFSEPGTYTYYCEPHRgaGMVGKIVVQ 91
Cdd:COG3794  1 MAFEPATLTVKPGDTVTWVNTDSVPHNVTSDDGPDGAFDSGLLAPGETFSVTFDEPGTYDYYCTPHP--WMVGTIVVG 76

Plastocyanin is a type I copper protein and functions in the electron transfer from PSII to PSI; Plastocyanin is a small copper-containing protein found in cyanobacteria, higher plants, and some algae, where it plays a role in photosynthesis. The two photosystems that are primarily responsible for photosynthesis are photosystem I (PSI) and photosystem II (PSII). The flow of electrons begins in PSII, which acts as a proton pump. Plastocyanin is responsible for transporting electrons from PSII to PSI.

                       10        20        30        40        50        60        70        80
               ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A       5 IKMGADNGMLAFEPSTIEIQAGDTVQWVNNKLAPHNVVVEGQP--------ELSHKDLAFSPGETFEATFSEPGTYTYYC 76
Cdd:cd04219  3 VKMGSDSGALVFEPKELTVKAGDTVEFVNNKGGPHNVVFDEDAvpsavdaaALSHKDLLNAPGETFSVTFPAPGTYTFYC 82

                       90
               ....*....|....*
1BXU_A      77 EPHRGAGMVGKIVVQ 91
Cdd:cd04219 83 EPHRGAGMVGKITVQ 97

Small blue copper proteins including pseudocyanin, plastocyanin, halocyanin and amicyanin; The Pseudocyanin-like family of copper-binding proteins (or blue (type 1) copper domain) is a family of small proteins that bind a single copper atom and are characterized by an intense electronic absorption band near 600 nm. Pseudoazurin (PAz) has been identified as a electron donor in the denitrification pathway. For example, PAz acts as an electron donor to cytochrome c peroxidase and N2OR from Paracoccus pantotrophus (Pp), and to the copper containing nitrite reductase (NiR) that catalyzes the second step of denitrification. Plastocyanin is found in cyanobacteria, higher plants, and some algae where it plays a role in photosynthesis. Plastocyanin is responsible for transporting electrons from PSII to PSI. This family also includes halocyanins found in halophilic archaea such as Natronomonas pharaonis (Natronobacterium pharaonis) and amicyanin found in bacteria Paracoccus denitrificans.

                       10        20        30        40        50        60        70        80
               ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A       3 VAIKMGADNGMLAFEPSTIEIQAGDTVQWVNNKLAPHNVV-----VEGQPELSHKDLAFSPGETFEATFSEPGTYTYYCE 77
Cdd:cd04204  1 VVVKMGADNGAMAFEPAAIRVDAGETVEFVNTGGGPHNVVfdkeiVPDGDAEFESDRVDEEGFTYEQTFDEPGVYGYYCT 80

                       90
               ....*....|..
1BXU_A      78 PHRGAGMVGKIV 89
Cdd:cd04204 81 PHRGAGMVGTVI 92

Halocyanin is an archaea blue (type I) copper redox protein; Halocyanins are blue (type I) copper redox proteins found in halophilic archaea such as Natronomonas pharaonis (Natronobacterium pharaonis). Halocyanin may serve as a mobile electron carrier at a peripheral membrane protein. The copper-binding domain is present only once in some halocyanins and is duplicated in others.

                       10        20        30        40        50        60        70        80
               ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A       1 QTVAIKMgadNGMLAFEPSTIEIQAGDTVQWVNN-KLAPHNVVVEGQPELSHKD--LAFSPGETFEATFSEPGTYTYYCE 77
Cdd:cd04220  2 VTVGVGM---NGGFAFDPAAIRVSPGTTVTWEWTgEGGGHNVVAYEDPITAFDSgsTDSSEGETYEHTFEETGEYRYVCV 78

                       90
               ....*....|...
1BXU_A      78 PHRGAGMVGKIVV 90
Cdd:cd04220 79 PHEALGMKGAIVV 91

Amicyanin is a type I blue copper protein that plays an essential role in electron transfer; In Paracoccus denitrificans bacteria, amicyanin acts as an intermediary of a three-member redox complex along with methylamine dehydrogenase (MADH) and cytochrome c-551i. The electron is transferred from the active site of MADH via the amicyanin copper ion to the cytochrome heme iron. The electron transfer from MADH to cytochrome c-551i does not involve a ternary complex but occurs via a ping-pong mechanism in which amicyanin uses the same interface for the reactions with MADH and cytochrome c-551i.

                       10        20        30        40        50        60        70        80
               ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A       1 QTVAIKmgadnGMlAFEPSTIEIQAGDTVQWVNNKLAPHNVVVEgqpELSHKDLAFSPGETFEATFSEPGTYTYYCEPHr 80
Cdd:cd13921  2 HVVTIE-----DF-KFNPAEVTVKVGDTVTWTNKDSVPHTVTAE---DGAFDSGMLATGKSFSYTFTAAGTYDYFCTIH- 71

                       90
               ....*....|
1BXU_A      81 gAGMVGKIVV 90
Cdd:cd13921 72 -PFMKGTVTV 80

pseudoazurin; Pseudoazurin, also called cupredoxin, is a small, blue periplasmic protein with a single bound copper atom. Pseudoazurin is related plastocyanins. Several examples of pseudoazurin are encoded by a neighboring gene for, or have been shown to transfer electrons to, copper-containing nitrite reductases (TIGR02376) of the same species. [Energy metabolism, Electron transport]

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A         12 GMLAFEPSTIEIQAGDTVQWVNNKLApHNV-VVEGQPELSHKDLAFSPGETFEATFSEPGTYTYYCEPHRGAGMVGKIVV 90
Cdd:TIGR02375   8 GAMVFEPAYIRAAPGDTVTFVPTDKG-HNVeTIKGMIPEGAEAFKSKINEEYTVTLTKEGVYGVKCTPHYGMGMVGLIQV 86

Cupredoxin superfamily; Cupredoxins contain type I copper centers and are involved in inter-molecular electron transfer reactions. Cupredoxins are blue copper proteins, having an intense blue color due to the presence of a mononuclear type 1 (T1) copper site. 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. Some of these proteins have lost the ability to bind copper. The majority of family members contain multiple cupredoxin domain repeats: ceruloplasmin and the coagulation factors V/VIII have six repeats; laccase, ascorbate oxidase, spore coat protein A, and multicopper oxidase CueO contain three repeats; and nitrite reductase has two repeats. Others are mono-domain cupredoxins, such as plastocyanin, pseudoazurin, plantacyanin, azurin, rusticyanin, stellacyanin, quinol oxidase, and the periplasmic domain of cytochrome c oxidase subunit II.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A       11 NGMLAFEPSTIEIQAGDTVQW--VNNKLAPHNVVV--EGQPELSHKDLAFS---------PGETFEATF--SEPGTYTYY 75
Cdd:cd00920  15 NGVLLFGPPVLVVPVGDTVRVqfVNKLGENHSVTIagFGVPVVAMAGGANPglvntlvigPGESAEVTFttDQAGVYWFY 94

                        90
                ....*....|....*
1BXU_A       76 C--EPHRGAGMVGKI 88
Cdd:cd00920  95 CtiPGHNHAGMVGTI 109

Auracyanins A and B and similar proteins; This subfamily includes both auracyanins A and B from the photosynthetic bacterium Chloroflexus aurantiacus and similar proteins. Auracyanins A and B are very similar blue copper proteins with 38% sequence identity and are homologous to the bacterial redox protein Azurin. However, auracyanin A is expressed only when C. aurantiacus cells are grown in light, whereas auracyanin B is expressed in both dark and light conditions. Thus, auracyanin A may function as a redox partner in photosynthesis, while auracyanin B may function in aerobic respiration.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A        3 VAIKMGADNGMLAFEPSTIEIQAGDTVQWV--NNKLAPHNVVV------------------EGQ-----PE----LSHKD 53
Cdd:cd04233   2 TTITIKAVPGELKFDKTRLTVKAGSKVTLTfeNPDDMPHNLVIvkpgslekvgeaalamgaDGPaknyvPDspdvLAATP 81

                        90       100       110       120
                ....*....|....*....|....*....|....*....|.
1BXU_A       54 LAfSPGETFEATF---SEPGTYTYYCE-PHRGAGMVGKIVV 90
Cdd:cd04233  82 LV-NPGETETLTFtapTEPGTYPYVCTyPGHWAIMKGVLIV 121

Uncharacterized Cupredoxin-like subfamily; Cupredoxins contain type I copper centers and are involved in inter-molecular electron transfer reactions. Cupredoxins are blue copper proteins because they have an intense blue color due to the presence of a mononuclear type 1 (T1) copper site. 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. Some of these proteins have lost the ability to bind copper. Majority of family members contain multiple cupredoxin domain repeats; ceruloplasmin and coagulation factors V/VIII have six repeats; Laccase, ascorbate oxidase, and spore coat protein A, and multicopper oxidase CueO contain three repeats; and nitrite reductase has two repeats. Others are mono-domain cupredoxins, such as plastocyanin, pseudoazurin, plantacyanin, azurin, rusticyanin, stellacyanin, quinol oxidase and the periplasmic domain of cytochrome c oxidase subunit II.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A        1 QTVAIKMgadNGMLAFEPSTIEIQAGDTVQWV--NNKLAPHNVVVEGQPEL-SHKDL---------------AFSPGETF 62
Cdd:cd04211   2 RTIEVTM---SDTMRFTPDSIQVKQGETVRFVvtNNGKIPHEFVIGTAAELkEHAEMmrkhpgmehdepnmvSLAPGKSG 78

                        90       100       110
                ....*....|....*....|....*....|..
1BXU_A       63 EA--TFSEPGTYTYYC-EP-HRGAGMVGKIVV 90
Cdd:cd04211  79 EIvwTFTKAGTFEFAClIPgHYEAGMVGKVTV 110

L-ascorbate oxidase, plant type; Members of this protein family are the copper-containing enzyme L-ascorbate oxidase (EC 1.10.3.3), also called ascorbase. This family is found in flowering plants, and shows greater sequence similarity to a family of laccases (EC 1.10.3.2) from plants than to other known ascorbate oxidases.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A         20 TIEIQAGDT-VQWVNNKLAPHNVVVE-------GQP----ELSHKDLAFSPGETFEATF--SEPGTYTYYcePH----RG 81
Cdd:TIGR03388  33 TIRAQAGDTiVVELTNKLHTEGVVIHwhgirqiGTPwadgTAGVTQCAINPGETFIYNFvvDRPGTYFYH--GHygmqRS 110

                  ....*....
1BXU_A         82 AGMVGKIVV 90
Cdd:TIGR03388 111 AGLYGSLIV 119

The C-terminal cupredoxin domain of Nitrous-oxide reductase; Nitrous-oxide reductase participates in nitrogen metabolism and catalyzes the last step in dissimilatory nitrate reduction, the two-electron reduction of N2O to N2. It contains copper ions as cofactors in the form of a binuclear CuA center at the site of electron entry and a tetranuclear CuZ centre at the active site. The C-terminus of Nitrous-oxide reductase is a cupredoxin domain.

                       10        20        30        40        50        60
               ....*....|....*....|....*....|....*....|....*....|....*....|....*....
1BXU_A      15 AFEPSTIEIQAGDTVQW-VNN----KLAPHNVVVEGQPelshKDLAFSPGETFEATF--SEPGTYTYYC 76
Cdd:cd04223 12 HFTPDIIEVKEGDEVTVhLTNleqdEDITHGFAIPGYN----VNLSLEPGETATVTFvaDKPGVYPYYC 76

Methylamine utilization protein MauL; MauL is one of the products from the methylamine utilization gene cluster in Methylobacterium extorquens AM1. Mutants generated by insertions in mauL were not able to grow on methylamine or any other primary amine as carbon sources. MauL belongs to the blue or type I copper protein family. They are involved in electron transfer reactions with the Cu center transitioning between the oxidized Cu(II) form and the reduced Cu(I) form.

                       10        20        30        40        50        60        70
               ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
1BXU_A      16 FEPSTIEIQAGDTVQWVNNKLAPHNVVVEgQPELSHKDLAFSPGETFEAT-FSEPGTYTYYCEPHrgAGMVGKIVV 90
Cdd:cd04221 11 FEPHVLVIKPGDTVSFPNSDDIRHNVYSF-SPAKIFELLDQPPGTTKDVVlFDKAGVVVVGCNIH--PIMRAWILV 83

Cupredoxin domain 1 of Copper-containing nitrite reductase; Copper-containing nitrite reductase (CuNIR), which catalyzes the reduction of NO2- to NO, is the key enzyme in the denitrification process in denitrifying bacteria. CuNIR contains at least one type 1 copper center and a type 2 copper center, which serves as the active site of the enzyme. A histidine, bound to the Type 2 Cu center, is responsible for binding and reducing nitrite. A Cys-His bridge plays an important role in facilitating rapid electron transfer from the type 1 center to the type 2 center. A reduced type I blue copper protein (pseudoazurin) was found to be a specific electron transfer donor for the copper-containing NIR in bacteria Alcaligenes faecalis.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A       20 TIEIQAGDTVQW--VNNKLA--PHNV---VVEGQPELSHKDLAfsPGETFEATFS--EPGTYTYYCEP-----HRGAGMV 85
Cdd:cd11020  34 VIRVREGDTVELtlTNPGTNtmPHSIdfhAATGPGGGEFTTIA--PGETKTFSFKalYPGVFMYHCATapvlmHIANGMY 111

                ....*.
1BXU_A       86 GKIVVQ 91
Cdd:cd11020 112 GAIIVE 117

Azurin and similar redox proteins; Azurin is a bacterial blue copper-binding protein. It serves as a redox partner to enzymes such as nitrite reductase or arsenite oxidase. The copper of Azurin is tetrahedrally coordinated by a cysteine, 2 histidines, and a methionine residue. The electron transfer reactions are carried out with the Cu center transitioning between the oxidized Cu(II) form and the reduced Cu(I) form. Azurin can function as tumor suppressor; it forms a complex with p53 that triggers apoptosis in various human cancer cells. Auracyanins A and B are from photosynthetic bacteria. They are very similar blue copper proteins with 38% sequence identity and they are homologous to the bacterial redox protein Azurin. However, auracyanin A is expressed only when C. aurantiacus cells are grown in light, whereas auracyanin B is expressed under dark and in light. Thus, auracyanin A may function as a redox partner in photosynthesis, while auracyanin B may function in aerobic respiration.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
1BXU_A       11 NGMLAFEPSTIEIQAGD---TVQWVNNKLAP-----HN-----------VVVEGQ---------PELSHKDLAFSP---- 58
Cdd:cd13843   7 NDEMQFSKTSITVSASCkefTVNLKHNGKLPknvmgHNwvlvksadaggVANAGMaagadnnylKPDDSRVIAHTPligg 86

                        90       100       110
                ....*....|....*....|....*....|....*...
1BXU_A       59 GETFEATF-----SEPGTYTYYCE-PHRGAGMVGKIVV 90
Cdd:cd13843  87 GETDSVTFtvsklEAGEDYTYFCTfPGHFALMKGTLTL 124