UniProtKB - P36551 (HEM6_HUMAN)
Oxygen-dependent coproporphyrinogen-III oxidase, mitochondrial
CPOX
Functioni
Catalyzes the aerobic oxidative decarboxylation of propionate groups of rings A and B of coproporphyrinogen-III to yield the vinyl groups in protoporphyrinogen-IX and participates to the sixth step in the heme biosynthetic pathway.
1 PublicationCatalytic activityi
: protoporphyrin-IX biosynthesis Pathwayi
This protein is involved in step 1 of the subpathway that synthesizes protoporphyrinogen-IX from coproporphyrinogen-III (O2 route).1 Publication This subpathway is part of the pathway protoporphyrin-IX biosynthesis, which is itself part of Porphyrin-containing compound metabolism.View all proteins of this organism that are known to be involved in the subpathway that synthesizes protoporphyrinogen-IX from coproporphyrinogen-III (O2 route), the pathway protoporphyrin-IX biosynthesis and in Porphyrin-containing compound metabolism.
Sites
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Binding sitei | 244 | SubstrateCurated | 1 | |
Active sitei | 258 | Proton donor1 Publication | 1 | |
Sitei | 327 | Important for dimerization | 1 |
GO - Molecular functioni
- coproporphyrinogen oxidase activity Source: UniProtKB
- protein homodimerization activity Source: UniProtKB
- structural constituent of eye lens Source: Ensembl
GO - Biological processi
- heme biosynthetic process Source: ProtInc
- protoporphyrinogen IX biosynthetic process Source: GO_Central
- response to arsenic-containing substance Source: Ensembl
- response to insecticide Source: Ensembl
- response to iron ion Source: Ensembl
- response to lead ion Source: Ensembl
- response to methylmercury Source: Ensembl
Keywordsi
Molecular function | Oxidoreductase |
Biological process | Heme biosynthesis, Porphyrin biosynthesis |
Enzyme and pathway databases
BRENDAi | 1.3.3.3, 2681 |
PathwayCommonsi | P36551 |
Reactomei | R-HSA-189451, Heme biosynthesis |
SignaLinki | P36551 |
UniPathwayi | UPA00251;UER00322 |
Names & Taxonomyi
Protein namesi | Recommended name: Oxygen-dependent coproporphyrinogen-III oxidase, mitochondrialCurated (EC:1.3.3.31 Publication)Short name: COX Short name: Coprogen oxidase Short name: Coproporphyrinogenase |
Gene namesi | |
Organismi | Homo sapiens (Human) |
Taxonomic identifieri | 9606 [NCBI] |
Taxonomic lineagei | Eukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Mammalia › Eutheria › Euarchontoglires › Primates › Haplorrhini › Catarrhini › Hominidae › Homo |
Proteomesi |
|
Organism-specific databases
HGNCi | HGNC:2321, CPOX |
MIMi | 612732, gene |
neXtProti | NX_P36551 |
VEuPathDBi | HostDB:ENSG00000080819 |
Subcellular locationi
Mitochondrion
Cytosol
- cytosol Source: HPA
Mitochondrion
- mitochondrial inner membrane Source: Ensembl
- mitochondrial intermembrane space Source: GO_Central
- mitochondrion Source: HPA
Other locations
- cytoplasm Source: GO_Central
Keywords - Cellular componenti
MitochondrionPathology & Biotechi
Involvement in diseasei
Hereditary coproporphyria (HCP)10 Publications
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Natural variantiVAR_084511 | 29 – 454 | Missing in HCP. 1 PublicationAdd BLAST | 426 | |
Natural variantiVAR_023444 | 135 | V → A in HCP. 1 PublicationCorresponds to variant dbSNP:rs201826432Ensembl. | 1 | |
Natural variantiVAR_002151 | 162 – 168 | Missing in HCP. 1 Publication | 7 | |
Natural variantiVAR_002152 | 189 | G → S in HCP; <5% of activity. 1 PublicationCorresponds to variant dbSNP:rs759347283Ensembl. | 1 | |
Natural variantiVAR_002153 | 197 | G → W in HCP. 1 Publication | 1 | |
Natural variantiVAR_002154 | 201 | E → K in HCP. 1 PublicationCorresponds to variant dbSNP:rs1374394802EnsemblClinVar. | 1 | |
Natural variantiVAR_019067 | 208 | S → F in HCP. 1 PublicationCorresponds to variant dbSNP:rs121917872EnsemblClinVar. | 1 | |
Natural variantiVAR_023445 | 214 | L → R in HCP. 1 Publication | 1 | |
Natural variantiVAR_023446 | 249 | P → R in HCP. 1 Publication | 1 | |
Natural variantiVAR_002155 | 249 | P → S in HCP. 1 Publication | 1 | |
Natural variantiVAR_058005 | 279 | G → R in HCP; a patient carrying also the L-12 mutation in ALAD. 1 PublicationCorresponds to variant dbSNP:rs121917874EnsemblClinVar. | 1 | |
Natural variantiVAR_002157 | 280 | G → R in HCP. 1 Publication | 1 | |
Natural variantiVAR_002159 | 295 | H → D in HCP. 1 PublicationCorresponds to variant dbSNP:rs121917870EnsemblClinVar. | 1 | |
Natural variantiVAR_019068 | 328 | R → C in HCP. 1 PublicationCorresponds to variant dbSNP:rs121917873EnsemblClinVar. | 1 | |
Natural variantiVAR_002160 | 331 | R → W in HCP. 2 PublicationsCorresponds to variant dbSNP:rs121917866EnsemblClinVar. | 1 | |
Natural variantiVAR_002161 | 390 | Missing in HCP. 1 Publication | 1 | |
Natural variantiVAR_002163 | 427 | W → R in HCP. 1 Publication | 1 | |
Natural variantiVAR_019069 | 447 | R → C in HCP. 1 PublicationCorresponds to variant dbSNP:rs28931603EnsemblClinVar. | 1 |
Harderoporphyria (HARPO)2 Publications
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Natural variantiVAR_084512 | 327 | H → R in HARPO. 1 PublicationCorresponds to variant dbSNP:rs587777271EnsemblClinVar. | 1 | |
Natural variantiVAR_002162 | 404 | K → E in HARPO. 1 PublicationCorresponds to variant dbSNP:rs121917868EnsemblClinVar. | 1 |
Mutagenesis
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Mutagenesisi | 392 – 418 | Missing : Loss for dimerization. 1 PublicationAdd BLAST | 27 |
Keywords - Diseasei
Disease variant, Hereditary hemolytic anemiaOrganism-specific databases
DisGeNETi | 1371 |
GeneReviewsi | CPOX |
MalaCardsi | CPOX |
MIMi | 121300, phenotype 618892, phenotype |
OpenTargetsi | ENSG00000080819 |
Orphaneti | 79273, Hereditary coproporphyria |
PharmGKBi | PA134979958 |
Miscellaneous databases
Pharosi | P36551, Tbio |
Chemistry databases
ChEMBLi | CHEMBL1681618 |
Genetic variation databases
BioMutai | CPOX |
DMDMi | 67476671 |
PTM / Processingi
Molecule processing
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Transit peptidei | 1 – 110 | MitochondrionBy similarityAdd BLAST | 110 | |
ChainiPRO_0000006029 | 111 – 454 | Oxygen-dependent coproporphyrinogen-III oxidase, mitochondrialAdd BLAST | 344 |
Amino acid modifications
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Modified residuei | 112 | PhosphoserineBy similarity | 1 | |
Modified residuei | 404 | N6-acetyllysine; alternateBy similarity | 1 | |
Modified residuei | 404 | N6-succinyllysine; alternateBy similarity | 1 |
Keywords - PTMi
Acetylation, PhosphoproteinProteomic databases
EPDi | P36551 |
jPOSTi | P36551 |
MassIVEi | P36551 |
MaxQBi | P36551 |
PaxDbi | P36551 |
PeptideAtlasi | P36551 |
PRIDEi | P36551 |
ProteomicsDBi | 55213 [P36551-1] |
PTM databases
GlyGeni | P36551, 1 site, 1 O-linked glycan (1 site) |
iPTMneti | P36551 |
PhosphoSitePlusi | P36551 |
SwissPalmi | P36551 |
Expressioni
Gene expression databases
Bgeei | ENSG00000080819, Expressed in liver and 224 other tissues |
ExpressionAtlasi | P36551, baseline and differential |
Genevisiblei | P36551, HS |
Organism-specific databases
HPAi | ENSG00000080819, Low tissue specificity |
Interactioni
Subunit structurei
Homodimer.
1 PublicationGO - Molecular functioni
- protein homodimerization activity Source: UniProtKB
Protein-protein interaction databases
BioGRIDi | 107763, 54 interactors |
IntActi | P36551, 32 interactors |
MINTi | P36551 |
STRINGi | 9606.ENSP00000264193 |
Miscellaneous databases
RNActi | P36551, protein |
Structurei
Secondary structure
3D structure databases
SMRi | P36551 |
ModBasei | Search... |
PDBe-KBi | Search... |
Miscellaneous databases
EvolutionaryTracei | P36551 |
Family & Domainsi
Region
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Regioni | 43 – 70 | DisorderedSequence analysisAdd BLAST | 28 | |
Regioni | 193 – 202 | Important for dimerizationCurated | 10 | |
Regioni | 260 – 262 | Substrate binding | 3 | |
Regioni | 392 – 428 | Important for dimerizationAdd BLAST | 37 | |
Regioni | 411 – 413 | Substrate binding | 3 |
Sequence similaritiesi
Keywords - Domaini
Transit peptidePhylogenomic databases
eggNOGi | KOG1518, Eukaryota |
GeneTreei | ENSGT00390000017311 |
HOGENOMi | CLU_026169_1_0_1 |
InParanoidi | P36551 |
OMAi | HDKGTLF |
OrthoDBi | 1080991at2759 |
PhylomeDBi | P36551 |
TreeFami | TF300703 |
Family and domain databases
Gene3Di | 3.40.1500.10, 1 hit |
InterProi | View protein in InterPro IPR001260, Coprogen_oxidase_aer IPR036406, Coprogen_oxidase_aer_sf IPR018375, Coprogen_oxidase_CS |
PANTHERi | PTHR10755, PTHR10755, 1 hit |
Pfami | View protein in Pfam PF01218, Coprogen_oxidas, 1 hit |
PRINTSi | PR00073, COPRGNOXDASE |
SUPFAMi | SSF102886, SSF102886, 1 hit |
PROSITEi | View protein in PROSITE PS01021, COPROGEN_OXIDASE, 1 hit |
s (2+)i Sequence
Sequence statusi: Complete.
: The displayed sequence is further processed into a mature form. Sequence processingi
This entry describes 2 produced by isoformsialternative splicing. AlignAdd to basketThis entry has 2 described isoforms and 1 potential isoform that is computationally mapped.Show allAlign All
This isoform has been chosen as the sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry. canonicali
10 20 30 40 50
MALQLGRLSS GPCWLVARGG CGGPRAWSQC GGGGLRAWSQ RSAAGRVCRP
60 70 80 90 100
PGPAGTEQSR GLGHGSTSRG GPWVGTGLAA ALAGLVGLAT AAFGHVQRAE
110 120 130 140 150
MLPKTSGTRA TSLGRPEEEE DELAHRCSSF MAPPVTDLGE LRRRPGDMKT
160 170 180 190 200
KMELLILETQ AQVCQALAQV DGGANFSVDR WERKEGGGGI SCVLQDGCVF
210 220 230 240 250
EKAGVSISVV HGNLSEEAAK QMRSRGKVLK TKDGKLPFCA MGVSSVIHPK
260 270 280 290 300
NPHAPTIHFN YRYFEVEEAD GNKQWWFGGG CDLTPTYLNQ EDAVHFHRTL
310 320 330 340 350
KEACDQHGPD LYPKFKKWCD DYFFIAHRGE RRGIGGIFFD DLDSPSKEEV
360 370 380 390 400
FRFVQSCARA VVPSYIPLVK KHCDDSFTPQ EKLWQQLRRG RYVEFNLLYD
410 420 430 440 450
RGTKFGLFTP GSRIESILMS LPLTARWEYM HSPSENSKEA EILEVLRHPR
DWVR
Computationally mapped potential isoform sequencesi
There is 1 potential isoform mapped to this entry.BLASTAlignShow allAdd to basketD6RER6 | D6RER6_HUMAN | Oxygen-dependent coproporphyrinogen... | CPOX | 175 | Annotation score: |
Sequence cautioni
Experimental Info
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Sequence conflicti | 247 | I → T in CAA82250 (PubMed:8159699).Curated | 1 |
Natural variant
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Natural variantiVAR_084511 | 29 – 454 | Missing in HCP. 1 PublicationAdd BLAST | 426 | |
Natural variantiVAR_023444 | 135 | V → A in HCP. 1 PublicationCorresponds to variant dbSNP:rs201826432Ensembl. | 1 | |
Natural variantiVAR_002151 | 162 – 168 | Missing in HCP. 1 Publication | 7 | |
Natural variantiVAR_002152 | 189 | G → S in HCP; <5% of activity. 1 PublicationCorresponds to variant dbSNP:rs759347283Ensembl. | 1 | |
Natural variantiVAR_002153 | 197 | G → W in HCP. 1 Publication | 1 | |
Natural variantiVAR_002154 | 201 | E → K in HCP. 1 PublicationCorresponds to variant dbSNP:rs1374394802EnsemblClinVar. | 1 | |
Natural variantiVAR_019067 | 208 | S → F in HCP. 1 PublicationCorresponds to variant dbSNP:rs121917872EnsemblClinVar. | 1 | |
Natural variantiVAR_023445 | 214 | L → R in HCP. 1 Publication | 1 | |
Natural variantiVAR_023446 | 249 | P → R in HCP. 1 Publication | 1 | |
Natural variantiVAR_002155 | 249 | P → S in HCP. 1 Publication | 1 | |
Natural variantiVAR_002156 | 272 | N → H2 PublicationsCorresponds to variant dbSNP:rs1131857EnsemblClinVar. | 1 | |
Natural variantiVAR_058005 | 279 | G → R in HCP; a patient carrying also the L-12 mutation in ALAD. 1 PublicationCorresponds to variant dbSNP:rs121917874EnsemblClinVar. | 1 | |
Natural variantiVAR_002157 | 280 | G → R in HCP. 1 Publication | 1 | |
Natural variantiVAR_002158 | 294 | V → I3 PublicationsCorresponds to variant dbSNP:rs2228056EnsemblClinVar. | 1 | |
Natural variantiVAR_002159 | 295 | H → D in HCP. 1 PublicationCorresponds to variant dbSNP:rs121917870EnsemblClinVar. | 1 | |
Natural variantiVAR_084512 | 327 | H → R in HARPO. 1 PublicationCorresponds to variant dbSNP:rs587777271EnsemblClinVar. | 1 | |
Natural variantiVAR_019068 | 328 | R → C in HCP. 1 PublicationCorresponds to variant dbSNP:rs121917873EnsemblClinVar. | 1 | |
Natural variantiVAR_002160 | 331 | R → W in HCP. 2 PublicationsCorresponds to variant dbSNP:rs121917866EnsemblClinVar. | 1 | |
Natural variantiVAR_048827 | 352 | R → C. Corresponds to variant dbSNP:rs11921054EnsemblClinVar. | 1 | |
Natural variantiVAR_002161 | 390 | Missing in HCP. 1 Publication | 1 | |
Natural variantiVAR_002162 | 404 | K → E in HARPO. 1 PublicationCorresponds to variant dbSNP:rs121917868EnsemblClinVar. | 1 | |
Natural variantiVAR_002163 | 427 | W → R in HCP. 1 Publication | 1 | |
Natural variantiVAR_019069 | 447 | R → C in HCP. 1 PublicationCorresponds to variant dbSNP:rs28931603EnsemblClinVar. | 1 |
Alternative sequence
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Alternative sequenceiVSP_057182 | 272 – 287 | NKQWW…LTPTY → KGLRSYGKYCRAKCAF in isoform 2. 1 PublicationAdd BLAST | 16 | |
Alternative sequenceiVSP_057183 | 288 – 454 | Missing in isoform 2. 1 PublicationAdd BLAST | 167 |
Sequence databases
Select the link destinations: EMBLi GenBanki DDBJi Links Updated | Z34531 , Z34803, Z34804, Z34805, Z34806, Z34807, Z34808 Genomic DNA Translation: CAA84292.1 AK290140 mRNA Translation: BAF82829.1 AK299692 mRNA Translation: BAG61597.1 AK223481 mRNA Translation: BAD97201.1 CH471052 Genomic DNA Translation: EAW79854.1 BC017210 mRNA Translation: AAH17210.1 BC023551 mRNA Translation: AAH23551.1 BC023554 mRNA Translation: AAH23554.1 D16611 mRNA Translation: BAA04033.1 Different initiation. Z28409 mRNA Translation: CAA82250.1 |
CCDSi | CCDS2932.1 [P36551-1] |
PIRi | I52444 |
RefSeqi | NP_000088.3, NM_000097.5 [P36551-1] |
Genome annotation databases
Ensembli | ENST00000647941; ENSP00000497326; ENSG00000080819 |
GeneIDi | 1371 |
KEGGi | hsa:1371 |
MANE-Selecti | ENST00000647941.2; ENSP00000497326.1; NM_000097.7; NP_000088.3 |
UCSCi | uc003dsx.4, human [P36551-1] |
Keywords - Coding sequence diversityi
Alternative splicingSimilar proteinsi
Cross-referencesi
Sequence databases
Select the link destinations: EMBLi GenBanki DDBJi Links Updated | Z34531 , Z34803, Z34804, Z34805, Z34806, Z34807, Z34808 Genomic DNA Translation: CAA84292.1 AK290140 mRNA Translation: BAF82829.1 AK299692 mRNA Translation: BAG61597.1 AK223481 mRNA Translation: BAD97201.1 CH471052 Genomic DNA Translation: EAW79854.1 BC017210 mRNA Translation: AAH17210.1 BC023551 mRNA Translation: AAH23551.1 BC023554 mRNA Translation: AAH23554.1 D16611 mRNA Translation: BAA04033.1 Different initiation. Z28409 mRNA Translation: CAA82250.1 |
CCDSi | CCDS2932.1 [P36551-1] |
PIRi | I52444 |
RefSeqi | NP_000088.3, NM_000097.5 [P36551-1] |
3D structure databases
Select the link destinations: PDBei RCSB PDBi PDBji Links Updated | PDB entry | Method | Resolution (Å) | Chain | Positions | PDBsum |
2AEX | X-ray | 1.58 | A | 111-454 | [»] | |
SMRi | P36551 | |||||
ModBasei | Search... | |||||
PDBe-KBi | Search... |
Protein-protein interaction databases
BioGRIDi | 107763, 54 interactors |
IntActi | P36551, 32 interactors |
MINTi | P36551 |
STRINGi | 9606.ENSP00000264193 |
Chemistry databases
ChEMBLi | CHEMBL1681618 |
PTM databases
GlyGeni | P36551, 1 site, 1 O-linked glycan (1 site) |
iPTMneti | P36551 |
PhosphoSitePlusi | P36551 |
SwissPalmi | P36551 |
Genetic variation databases
BioMutai | CPOX |
DMDMi | 67476671 |
Proteomic databases
EPDi | P36551 |
jPOSTi | P36551 |
MassIVEi | P36551 |
MaxQBi | P36551 |
PaxDbi | P36551 |
PeptideAtlasi | P36551 |
PRIDEi | P36551 |
ProteomicsDBi | 55213 [P36551-1] |
Protocols and materials databases
Antibodypediai | 2788, 171 antibodies from 29 providers |
DNASUi | 1371 |
Genome annotation databases
Ensembli | ENST00000647941; ENSP00000497326; ENSG00000080819 |
GeneIDi | 1371 |
KEGGi | hsa:1371 |
MANE-Selecti | ENST00000647941.2; ENSP00000497326.1; NM_000097.7; NP_000088.3 |
UCSCi | uc003dsx.4, human [P36551-1] |
Organism-specific databases
CTDi | 1371 |
DisGeNETi | 1371 |
GeneCardsi | CPOX |
GeneReviewsi | CPOX |
HGNCi | HGNC:2321, CPOX |
HPAi | ENSG00000080819, Low tissue specificity |
MalaCardsi | CPOX |
MIMi | 121300, phenotype 612732, gene 618892, phenotype |
neXtProti | NX_P36551 |
OpenTargetsi | ENSG00000080819 |
Orphaneti | 79273, Hereditary coproporphyria |
PharmGKBi | PA134979958 |
VEuPathDBi | HostDB:ENSG00000080819 |
GenAtlasi | Search... |
Phylogenomic databases
eggNOGi | KOG1518, Eukaryota |
GeneTreei | ENSGT00390000017311 |
HOGENOMi | CLU_026169_1_0_1 |
InParanoidi | P36551 |
OMAi | HDKGTLF |
OrthoDBi | 1080991at2759 |
PhylomeDBi | P36551 |
TreeFami | TF300703 |
Enzyme and pathway databases
UniPathwayi | UPA00251;UER00322 |
BRENDAi | 1.3.3.3, 2681 |
PathwayCommonsi | P36551 |
Reactomei | R-HSA-189451, Heme biosynthesis |
SignaLinki | P36551 |
Miscellaneous databases
BioGRID-ORCSi | 1371, 201 hits in 1057 CRISPR screens |
ChiTaRSi | CPOX, human |
EvolutionaryTracei | P36551 |
GeneWikii | Coproporphyrinogen_III_oxidase |
GenomeRNAii | 1371 |
Pharosi | P36551, Tbio |
PROi | PR:P36551 |
RNActi | P36551, protein |
SOURCEi | Search... |
Gene expression databases
Bgeei | ENSG00000080819, Expressed in liver and 224 other tissues |
ExpressionAtlasi | P36551, baseline and differential |
Genevisiblei | P36551, HS |
Family and domain databases
Gene3Di | 3.40.1500.10, 1 hit |
InterProi | View protein in InterPro IPR001260, Coprogen_oxidase_aer IPR036406, Coprogen_oxidase_aer_sf IPR018375, Coprogen_oxidase_CS |
PANTHERi | PTHR10755, PTHR10755, 1 hit |
Pfami | View protein in Pfam PF01218, Coprogen_oxidas, 1 hit |
PRINTSi | PR00073, COPRGNOXDASE |
SUPFAMi | SSF102886, SSF102886, 1 hit |
PROSITEi | View protein in PROSITE PS01021, COPROGEN_OXIDASE, 1 hit |
MobiDBi | Search... |
Entry informationi
Entry namei | HEM6_HUMAN | |
Accessioni | P36551Primary (citable) accession number: P36551 Secondary accession number(s): A8K275 Q96AF3 | |
Entry historyi | Integrated into UniProtKB/Swiss-Prot: | June 1, 1994 |
Last sequence update: | June 7, 2005 | |
Last modified: | February 23, 2022 | |
This is version 209 of the entry and version 3 of the sequence. See complete history. | ||
Entry statusi | Reviewed (UniProtKB/Swiss-Prot) | |
Annotation program | Chordata Protein Annotation Program | |
Disclaimer | Any medical or genetic information present in this entry is provided for research, educational and informational purposes only. It is not in any way intended to be used as a substitute for professional medical advice, diagnosis, treatment or care. |
Miscellaneousi
Keywords - Technical termi
3D-structure, Reference proteomeDocuments
- Human chromosome 3
Human chromosome 3: entries, gene names and cross-references to MIM - Human entries with genetic variants
List of human entries with genetic variants - Human variants curated from literature reports
Index of human variants curated from literature reports - MIM cross-references
Online Mendelian Inheritance in Man (MIM) cross-references in UniProtKB/Swiss-Prot - PATHWAY comments
Index of metabolic and biosynthesis pathways - PDB cross-references
Index of Protein Data Bank (PDB) cross-references - SIMILARITY comments
Index of protein domains and families