Reviewed, UniProtKB/Swiss-Prot P00173 (CYB5_RAT)

Names and origin

Protein names

Recommended name:
    Cytochrome b5

Gene names

Name:	Cyb5a
Synonyms:	Cyb5

Organism

Rattus norvegicus (Rat)

Taxonomic identifier

10116 [NCBI]

Taxonomic lineage

Eukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Mammalia › Eutheria › Euarchontoglires › Glires › Rodentia › Sciurognathi › Muroidea › Muridae › Murinae › Rattus

Protein attributes

Sequence length	134 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is further processed into a mature form.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	Cytochrome b5 is a membrane bound hemoprotein which function as an electron carrier for several membrane bound oxygenases. It is also involved in several steps of the sterol biosynthesis pathway, particularly in the C-6 double bond introduction during the C-6 desaturation.
Subcellular location	Endoplasmic reticulum membrane; Single-pass membrane protein; Cytoplasmic side. Microsome membrane; Single-pass membrane protein; Cytoplasmic side.
Sequence similarities	Belongs to the cytochrome b5 family. Contains 1 cytochrome b5 heme-binding domain.

Ontologies

Keywords
Biological process	Electron transport Transport
Cellular component	Endoplasmic reticulum Membrane Microsome
Coding sequence diversity	Alternative splicing
Domain	Transmembrane
Ligand	Heme Iron Metal-binding
PTM	Acetylation
Technical term	3D-structure Direct protein sequencing
Gene Ontology (GO)
Biological process	electron transport chain Inferred from electronic annotation. Source: UniProtKB-KW response to cadmium ion Inferred from expression pattern. Source: RGD transport Inferred from electronic annotation. Source: UniProtKB-KW
Cellular component	endoplasmic reticulum membrane Inferred from direct assay. Source: RGD integral to membrane Inferred from electronic annotation. Source: UniProtKB-KW microsome Inferred from electronic annotation. Source: UniProtKB-SubCell
Molecular function	electron carrier activity Ref.2 Traceable author statement. Source: RGD heme binding Inferred from electronic annotation. Source: InterPro
Complete GO annotation...

Alternative products

This entry describes 2 isoforms produced by alternative splicing. [Align] [Select]

Isoform Long (identifier: P00173-1)

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 Short (identifier: P00173-2)

The sequence of this isoform differs from the canonical sequence as follows:
     97-100: ETLI → HSAL
     101-134: Missing.

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Initiator methionine

1

1

Removed Ref.4 Ref.5

Chain

2 – 134

133

Cytochrome b5

PRO_0000166014

Regions

Transmembrane

109 – 131

23

Potential

Domain

9 – 85

77

Cytochrome b5 heme-binding

Sites

Metal binding

44

1

Iron (heme axial ligand)

Metal binding

68

1

Iron (heme axial ligand)

Amino acid modifications

Modified residue

2

1

N-acetylalanine Ref.4

Modified residue

19

1

N6-acetyllysine By similarity

Natural variations

Alternative sequence

97 – 100

4

ETLI → HSAL in isoform Short.

VSP_001246

Alternative sequence

101 – 134

34

Missing in isoform Short.

VSP_001247

Experimental info

Sequence conflict

18

1

Q → E AA sequence Ref.6

Secondary structure

1

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

134

Helix Strand Turn

Details...

Helix

14 – 19

6

Beta strand

21 – 24

4

Beta strand

27 – 29

3

Beta strand

34 – 36

3

Helix

40 – 42

3

Helix

47 – 52

6

Turn

53 – 56

4

Helix

60 – 64

5

Helix

70 – 74

5

Helix

76 – 79

4

Helix

88 – 90

3

Sequences

	Sequence		Length	Mass (Da)
	Isoform Long [UniParc]. Last modified January 23, 2007. Version 2. Checksum: 37568069CA88CCD2	FASTA	134	15,355
	10 20 30 40 50 60 MAEQSDKDVK YYTLEEIQKH KDSKSTWVIL HHKVYDLTKF LEEHPGGEEV LREQAGGDAT 70 80 90 100 110 120 ENFEDVGHST DARELSKTYI IGELHPDDRS KIAKPSETLI TTVESNSSWW TNWVIPAISA 130 LVVALMYRLY MAED
	Isoform Short. Checksum: 8D8AC05DCA93F37D	FASTA	100	11,407
	10 20 30 40 50 60 MAEQSDKDVK YYTLEEIQKH KDSKSTWVIL HHKVYDLTKF LEEHPGGEEV LREQAGGDAT 70 80 90 100 ENFEDVGHST DARELSKTYI IGELHPDDRS KIAKPSHSAL

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"The carboxy-terminal 10 amino acid residues of cytochrome b5 are necessary for its targeting to the endoplasmic reticulum." Mitoma J.-Y., Ito A. EMBO J. 11:4197-4203(1992) [PubMed: 1396600] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA].
[2]	"Identification of two homologous cytochrome b5s in rat brain." Yoo M. Biochem. Biophys. Res. Commun. 236:641-642(1997) [PubMed: 9245704] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA], ALTERNATIVE SPLICING. Strain: Sprague-Dawley. Tissue: Brain.
[3]	"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 LONG). Tissue: Liver.
[4]	"Chemical structure of rat liver cytochrome b5. Isolation of peptides by high-pressure liquid chromatography." Ozols J., Heinemann F.S. Biochim. Biophys. Acta 704:163-173(1982) [PubMed: 7093287] [Abstract] Cited for: PROTEIN SEQUENCE OF 2-134.
[5]	"Structure of cytochrome b5 and its topology in the microsomal membrane." Ozols J. Biochim. Biophys. Acta 997:121-130(1989) [PubMed: 2752049] [Abstract] Cited for: PROTEIN SEQUENCE OF 2-11.
[6]	"Two homologous cytochromes b5 in a single cell." Lederer F., Ghrir R., Guiard B., Cortial S., Ito A. Eur. J. Biochem. 132:95-102(1983) [PubMed: 6840088] [Abstract] Cited for: PROTEIN SEQUENCE OF 7-89.
[7]	"Design challenges for hemoproteins: the solution structure of apocytochrome b5." Falzone C.J., Mayer M.R., Whiteman E.L., Moore C.D., Lecomte J.T.J. Biochemistry 35:6519-6526(1996) [PubMed: 8639599] [Abstract] Cited for: STRUCTURE BY NMR OF 1-99.
[8]	"Solution structure of reduced microsomal rat cytochrome b5." Banci L., Bertini I., Ferroni F., Rosato A. Eur. J. Biochem. 249:270-279(1997) [PubMed: 9363779] [Abstract] Cited for: STRUCTURE BY NMR OF 6-99.
[9]	"The solution structure of oxidized rat microsomal cytochrome b5." Arnesano F., Banci L., Bertini I., Felli I.C. Biochemistry 37:173-184(1998) [PubMed: 9425037] [Abstract] Cited for: STRUCTURE BY NMR OF 6-99.
[10]	"The origin of differences in the physical properties of the equilibrium forms of cytochrome b5 revealed through high-resolution NMR structures and backbone dynamic analyses." Dangi B., Sarma S., Yan C., Banville D.L., Guiles R.D. Biochemistry 37:8289-8302(1998) [PubMed: 9622481] [Abstract] Cited for: STRUCTURE BY NMR OF 6-99.
[11]	"Structural and dynamic perturbations induced by heme binding in cytochrome b5." Falzone C.J., Wang Y., Vu B.C., Scott N.L., Bhattacharya S., Lecomte J.T.J. Biochemistry 40:4879-4891(2001) [PubMed: 11294656] [Abstract] Cited for: STRUCTURE BY NMR OF 1-99.
+	Additional computationally mapped references.

Cross-references

Sequence databases

EMBLGenBankDDBJ

D13205 mRNA. Translation: BAA02492.1.
AF007107 mRNA. Translation: AAB67609.1.
AF007108 mRNA. Translation: AAB67610.1.
BC086945 mRNA. Translation: AAH86945.1.

IPI

IPI00231013.
IPI00286154.

PIR

JC5596.
CBRT5. S28404.

RefSeq

NP_071581.1.

UniGene

Rn.1055

3D structure databases

PDBPDBe

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1AQA	NMR	-	A	6-99	[»]
1AW3	NMR	-	A	6-99	[»]
1AXX	NMR	-	A	6-99	[»]
1B5A	NMR	-	A	6-99	[»]
1B5B	NMR	-	A	6-99	[»]
1BFX	NMR	-	A	2-98	[»]
1BLV	NMR	-	A	6-98	[»]
1I87	NMR	-	A	2-99	[»]
1I8C	NMR	-	A	2-99	[»]
1IB7	NMR	-	A	6-98	[»]
1IET	NMR	-	A	2-99	[»]
1IEU	NMR	-	A	2-99	[»]
1JEX	NMR	-	A	6-98	[»]
1MNY	NMR	-	A	6-98	[»]
2AXX	NMR	-	A	6-99	[»]

ModBase

Search...

Proteomic databases

PRIDE

P00173.

Genome annotation databases

Ensembl

ENSRNOG00000015205. Rattus norvegicus. [Contig view]

GeneID

64001.

KEGG

rno:64001.

Organism-specific databases

RGD

620558. Cyb5.

Phylogenomic databases

HOVERGEN

P00173.

OMA

P00173. QKHNHSK.

Gene expression databases

ArrayExpress

P00173.

GermOnline

ENSRNOG00000015205. Rattus norvegicus.

Family and domain databases

InterPro

IPR001199. Cyt_B5.
IPR018506. Cyt_B5_heme-BS.
[Graphical view]

Gene3D

G3DSA:3.10.120.10. Cyt_B5. 1 hit.

Pfam

PF00173. Cyt-b5. 1 hit.
[Graphical view]

PRINTS

PR00363. CYTOCHROMEB5.

ProDom

PD000612. Cyt_B5. 1 hit.
[Graphical view] [Entries sharing at least one domain]

PROSITE

PS00191. CYTOCHROME_B5_1. 1 hit.
PS50255. CYTOCHROME_B5_2. 1 hit.
[Graphical view]

ProtoNet

Search...

Other Resources

NextBio

612578.

Entry information

Entry name

CYB5_RAT

Accession

Primary (citable) accession number: P00173
Secondary accession number(s): O35768

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 21, 1986
Last sequence update:	January 23, 2007
Last modified:	June 16, 2009
This is version 97 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

HPI (Human Proteome Initiative)