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Q68EJ0 (NB5R4_RAT) Reviewed, UniProtKB/Swiss-Prot

Last modified September 21, 2011. Version 63. Feed History...

Clusters with 100%, 90%, 50% identity | Documents (1) | Third-party data text xml rdf/xml gff fasta
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Names and origin

Protein namesRecommended name:
Cytochrome b5 reductase 4
EC=1.6.2.2
Alternative name(s):
Flavohemoprotein b5/b5R
Short name=b5+b5R
N-terminal cytochrome b5 and cytochrome b5 oxidoreductase domain-containing protein
cb5/cb5R
Gene names
Name:Cyb5r4
Synonyms:Ncb5or
OrganismRattus norvegicus (Rat)
Taxonomic identifier10116 [NCBI]
Taxonomic lineageEukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Mammalia › Eutheria › Euarchontoglires › Glires › Rodentia › Sciurognathi › Muroidea › Muridae › Murinae › Rattus

Protein attributes

Sequence length520 AA.
Sequence statusComplete.
Protein existenceEvidence at protein level

General annotation (Comments)

Function

NADH-cytochrome b5 reductase involved in endolasmic reticulum stress response pathway. Plays a critical role in protecting pancreatic beta-cells against oxidant stress, possibly by protecting the cell from excess buildup of reactive oxygen species (ROS).

Catalytic activity

NADH + 2 ferricytochrome b5 = NAD+ + H+ + 2 ferrocytochrome b5. Ref.2

Cofactor

FAD.

Subcellular location

Endoplasmic reticulum. Note: Soluble protein By similarity.

Tissue specificity

Isoform 2 is expressed in testis, brain, skeletal muscle and in the male germline. Ref.3

Sequence similarities

Belongs to the flavoprotein pyridine nucleotide cytochrome reductase family.

Contains 1 CS domain.

Contains 1 cytochrome b5 heme-binding domain.

Contains 1 FAD-binding FR-type domain.

Biophysicochemical properties

Kinetic parameters:

KM=28 µM for ferricyanide Ref.2

KM=1 µM for NADPH

KM=7 µM for cytochrome c

Sequence caution

The sequence AAH80240.1 differs from that shown. Reason: Erroneous initiation.

Alternative products

This entry describes 2 isoforms produced by alternative splicing. [Align] [Select]
Isoform 1 (identifier: Q68EJ0-1)

This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.
Isoform 2 (identifier: Q68EJ0-2)

Also known as: cb5/cb5rDelta12;

The sequence of this isoform differs from the canonical sequence as follows:
     318-368: Missing.

Sequence annotation (Features)

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifier

Molecule processing

Chain1 – 520520Cytochrome b5 reductase 4
PRO_0000287558

Regions

Domain54 – 13077Cytochrome b5 heme-binding
Domain164 – 25592CS
Domain272 – 384113FAD-binding FR-type
Nucleotide binding364 – 37916FAD By similarity
Nucleotide binding391 – 42333FAD By similarity

Sites

Metal binding891Iron (heme axial ligand)
Metal binding1121Iron (heme axial ligand)

Natural variations

Alternative sequence318 – 36851Missing in isoform 2.
VSP_025563

Experimental info

Mutagenesis891H → A or M: Abolishes heme-binding but does not affect reductase activity. Ref.2
Mutagenesis1121H → A or M: Abolishes heme-binding but does not affect reductase activity. Ref.2
Sequence conflict381F → I in AAH80240. Ref.1
Sequence conflict2441Q → L in AAG45053. Ref.2

Sequences

Sequence LengthMass (Da)Tools
Isoform 1 [UniParc].

Last modified May 15, 2007. Version 2.
Checksum: F0C0553206F7976A

FASTA52058,835
        10         20         30         40         50         60 
MLNVPSQAFP APGSQQRVAS QGRSKVPLKQ GRSLMDWFRL TKSGKDFTGL KGGLIEVTEE 

        70         80         90        100        110        120 
ELKKHNKKDD CWICIRGFVY NVSPYMEYHP GGEDELMRAA GADGTDLFNE VHRWVNYESM 

       130        140        150        160        170        180 
LKECLVGRMA VKPAVPKDCH EGKRVLNGML PKSQVTDTLP REGPSSPSYD WFQTESSVTI 

       190        200        210        220        230        240 
VIYTKQKNIN LDSVIVDLQD DSLRAEAVIK DHSYLIHIGL SHEVQENFSV RVIENVGKIE 

       250        260        270        280        290        300 
IVLQKKETVS WKCLGDPLEK HDSFIPKKDT GLYYRQCQLI SKEDVTHDTR LFCLMLPPST 

       310        320        330        340        350        360 
HLQVPVGQHV YLKLSVTGAE IVKPYTPVSE SLLSDFKEPV LSPNKYIYFL IKIYPAGLFT 

       370        380        390        400        410        420 
PELDRLQIGD FVSVSGPEGN FKVSKLQEVE DLFLLAAGTG FTPMVTVLNH ALTHMSSLRK 

       430        440        450        460        470        480 
VKLMFFNKTE DDIIWRCQLE KLALKDKRFH VEYVLSAPSP EWNGKQGHVS RALLSEFLQR 

       490        500        510        520 
SLENSKVFLC ICGPTPFTDE GIRLLHDLNF SDDEIHGFTA

« Hide

Isoform 2 (cb5/cb5rDelta12) [UniParc].

Checksum: F51B15B52318FFE2
Show »

FASTA46953,038

References

« Hide 'large scale' references
[1]"The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)."
The MGC Project Team
Genome Res. 14:2121-2127(2004) [PubMed: 15489334] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1).
Tissue: Lung.
[2]"Heterologous expression of an endogenous rat cytochrome b(5)/cytochrome b(5) reductase fusion protein: identification of histidines 62 and 85 as the heme axial ligands."
Davis C.A., Dhawan I.K., Johnson M.K., Barber M.J.
Arch. Biochem. Biophys. 400:63-75(2002) [PubMed: 11913972] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA] OF 35-520 (ISOFORM 1), ENZYME ACTIVITY, BIOPHYSICOCHEMICAL PROPERTIES, FAD-BINDING, HEME-BINDING AT HIS-89 AND HIS-112, MUTAGENESIS OF HIS-89 AND HIS-112.
[3]"Identification and characterization of a novel splice variant of mouse and rat cytochrome b5/cytochrome b5 reductase."
Curry B.J., Roman S.D., Wallace C.A., Scott R., Miriami E., Aitken R.J.
Genomics 83:425-438(2004) [PubMed: 14962668] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA] OF 35-520 (ISOFORMS 1 AND 2), TISSUE SPECIFICITY.
Strain: Wistar.
Tissue: Testis.
+Additional computationally mapped references.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ		BC080240 mRNA. Translation: AAH80240.1. Different initiation.
AF307840 mRNA. Translation: AAG45053.1.
AY321370 mRNA. Translation: AAQ83902.1.
AY321371 mRNA. Translation: AAQ83903.1.
IPIIPI00189672.
IPI00390401.
RefSeqNP_596918.2. NM_133427.2.
UniGeneRn.3334.

3D structure databases

HSSPHSSP built from PDB template 1QX4 based on UniProtKB P20070.
ProteinModelPortalQ68EJ0.
ModBaseSearch...

Protein-protein interaction databases

STRINGQ68EJ0.

PTM databases

PhosphoSiteQ68EJ0.

Proteomic databases

PRIDEQ68EJ0.

Protocols and materials databases

StructuralBiologyKnowledgebaseSearch...

Genome annotation databases

GeneID171015.
KEGGrno:171015.
UCSCNM_133427. rat.

Organism-specific databases

CTD51167.
RGD621834. Cyb5r4.

Phylogenomic databases

eggNOGroNOG07055.
GeneTreeENSGT00390000008881.
HOVERGENHBG108174.
InParanoidQ68EJ0.
PhylomeDBQ68EJ0.

Gene expression databases

ArrayExpressQ68EJ0.
GenevestigatorQ68EJ0.

Family and domain databases

InterProIPR007052. CS-like_domain.
IPR017447. CS_domain.
IPR001199. Cyt_B5.
IPR018506. Cyt_B5_heme-BS.
IPR017927. Fd_Rdtase_FAD-bd.
IPR008978. HSP20-like_chaperone.
IPR001834. NADH-Cyt_B5_reductase.
IPR008333. OxRdtase_FAD-bd_dom.
IPR001433. OxRdtase_FAD/NAD-bd.
IPR017938. Riboflavin_synthase-like_b-brl.
[Graphical view]
Gene3DG3DSA:3.10.120.10. Cyt_B5. 1 hit.
PfamPF04969. CS. 1 hit.
PF00173. Cyt-b5. 1 hit.
PF00970. FAD_binding_6. 1 hit.
PF00175. NAD_binding_1. 1 hit.
[Graphical view]
PRINTSPR00406. CYTB5RDTASE.
PR00363. CYTOCHROMEB5.
SUPFAMSSF55856. Cyt_B5. 1 hit.
SSF49764. HSP20_chap. 1 hit.
SSF63380. Riboflavin_synthase_like_b-brl. 1 hit.
PROSITEPS51203. CS. 1 hit.
PS00191. CYTOCHROME_B5_1. 1 hit.
PS50255. CYTOCHROME_B5_2. 1 hit.
PS51384. FAD_FR. 1 hit.
[Graphical view]
ProtoNetSearch...

Other

NextBio621501.

Entry information

Entry nameNB5R4_RAT
AccessionPrimary (citable) accession number: Q68EJ0
Secondary accession number(s): Q6VXY2, Q6VXY3, Q9EPZ4
Entry history
Integrated into UniProtKB/Swiss-Prot: May 15, 2007
Last sequence update: May 15, 2007
Last modified: September 21, 2011
This is version 63 of the entry and version 2 of the sequence. [Complete history]
Entry statusReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program

Relevant documents

SIMILARITY comments

Index of protein domains and families

to top of pageNames·Attributes·General annotation·Ontologies·Alt products·Sequence annotation·Sequences·References·Cross-refs·Entry info·Documents