P00169 (CYB5_RABIT) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Cytochrome b5

Gene names

Name:	CYB5A
Synonyms:	CYB5

Organism

Oryctolagus cuniculus (Rabbit) [Reference proteome]

Taxonomic identifier

9986 [NCBI]

Taxonomic lineage

cellular organisms › Eukaryota › Opisthokonta › Metazoa › Eumetazoa › Bilateria › Deuterostomia › Chordata › Craniata › Vertebrata › Gnathostomata › Teleostomi › Euteleostomi › Sarcopterygii › Tetrapoda › Amniota › Mammalia › Theria › Eutheria › Euarchontoglires › Glires › Lagomorpha › Leporidae › Oryctolagus

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.
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 Transmembrane helix
Ligand	Heme Iron Metal-binding
PTM	Acetylation
Technical term	3D-structure Complete proteome Direct protein sequencing Reference proteome
Gene Ontology (GO)
Biological_process	electron transport chain Inferred from electronic annotation. Source: UniProtKB-KW
Cellular_component	endoplasmic reticulum membrane Inferred from electronic annotation. Source: UniProtKB-SubCell integral to membrane Inferred from electronic annotation. Source: UniProtKB-KW mitochondrion Inferred from electronic annotation. Source: Compara
Molecular_function	heme binding Inferred from electronic annotation. Source: InterPro metal ion binding Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Alternative products

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

Isoform 1 (identifier: P00169-1)

Also known as: Liver; Membrane-bound;

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: P00169-2)

Also known as: Erythrocyte; Cytoplasmic;

The sequence of this isoform differs from the canonical sequence as follows:
     98-98: T → P
     99-134: Missing.

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Initiator methionine

1

1

Removed Ref.8

Chain

2 – 134

133

Cytochrome b5

PRO_0000166013

Regions

Transmembrane

109 – 131

23

Helical; 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.8

Modified residue

19

1

N6-acetyllysine By similarity

Natural variations

Alternative sequence

98

1

T → P in isoform 2.

VSP_001244

Alternative sequence

99 – 134

36

Missing in isoform 2.

VSP_001245

Experimental info

Sequence conflict

62

1

N → D AA sequence Ref.3

Sequence conflict

62

1

N → D AA sequence Ref.5

Sequence conflict

104

1

D → N AA sequence Ref.6

Secondary structure

1

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

134

Helix Strand Turn

Details...

Beta strand

10 – 12

3

Helix

14 – 17

4

Turn

18 – 20

3

Beta strand

22 – 25

4

Beta strand

27 – 36

10

Helix

38 – 40

3

Turn

41 – 43

3

Beta strand

44 – 46

3

Helix

49 – 53

5

Turn

54 – 56

3

Helix

60 – 66

7

Helix

70 – 79

10

Beta strand

80 – 84

5

Helix

86 – 88

3

Turn

89 – 91

3

Sequences

	Sequence		Length	Mass (Da)
	Isoform 1 (Liver) (Membrane-bound) [UniParc]. Last modified January 23, 2007. Version 4. Checksum: B748AE9D32FA5E46	FASTA	134	15,349
	10 20 30 40 50 60 MAAQSDKDVK YYTLEEIKKH NHSKSTWLIL HHKVYDLTKF LEEHPGGEEV LREQAGGDAT 70 80 90 100 110 120 ENFEDVGHST DARELSKTFI IGELHPDDRS KLSKPMETLI TTVDSNSSWW TNWVIPAISA 130 LIVALMYRLY MADD
	Isoform 2 (Erythrocyte) (Cytoplasmic) [UniParc]. Checksum: C3D197FD9C921C1D	FASTA	98	11,232
	10 20 30 40 50 60 MAAQSDKDVK YYTLEEIKKH NHSKSTWLIL HHKVYDLTKF LEEHPGGEEV LREQAGGDAT 70 80 90 ENFEDVGHST DARELSKTFI IGELHPDDRS KLSKPMEP

References

[1]	"The nucleotide sequence of rabbit liver cytochrome b5 mRNA." Dariush N., Fisher C.W., Steggles A.W. Protein Seq. Data Anal. 1:351-353(1988) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1).
[2]	"Molecular cloning of rabbit cytochrome b5 genes: evidence for the occurrence of two separate genes encoding the soluble and microsomal forms." Takamatsu H., Kozutsumi Y., Suzuki A., Kawasaki T. Biochem. Biophys. Res. Commun. 185:845-851(1992) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 2). Strain: New Zealand white.
[3]	"Primary structure of rabbit liver cytochrome b5." Tsugita A., Kobayashi M., Kajihara T., Hagihara B. J. Biochem. 64:727-730(1968) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE OF 9-46 AND 50-91.
[4]	"Comparative study of the primary structures of cytochrome b5 from four species." Tsugita A., Kobayashi M., Tani S., Kyo S., Rashid M.A., Yoshida Y., Kajihara T., Hagihara B. Proc. Natl. Acad. Sci. U.S.A. 67:442-447(1970) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE OF 7-8 AND 47-49.
[5]	"Amino acid sequence of rabbit liver microsomal cytochrome b5." Ozols J. J. Biol. Chem. 245:4863-4874(1970) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE OF 5-98.
[6]	"Primary structure of the membrane-binding segment of rabbit cytochrome b5." Kondo K., Tajima S., Sato R., Narita K. J. Biochem. 86:1119-1128(1979) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE OF 92-134.
[7]	"Amino acid sequence of the membranous segment of rabbit liver cytochrome b5. Methodology for separation of hydrophobic peptides." Takagaki Y., Gerber G.E., Nihei K., Khorana H.G. J. Biol. Chem. 255:1536-1541(1980) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE OF 99-134.
[8]	"Structure of cytochrome b5 and its topology in the microsomal membrane." Ozols J. Biochim. Biophys. Acta 997:121-130(1989) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE OF 2-11.
[9]	"Solution structure of oxidized microsomal rabbit cytochrome b5 factors determining the heterogeneous binding of the heme." Banci L., Bertini I., Rosato A., Scacchieri S. Eur. J. Biochem. 267:755-766(2000) [PubMed] [Europe PMC] [Abstract] Cited for: STRUCTURE BY NMR OF 7-100.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ

M24844 mRNA. Translation: AAB03878.1.
D10901 mRNA. Translation: BAA01712.1.

PIR

JN0316.
CBRB5. S03373.

RefSeq

NP_001164734.1. NM_001171263.1.
NP_001164735.1. NM_001171264.1.

UniGene

Ocu.2112.
Ocu.6903.

3D structure databases

PDBe
RCSB PDB
PDBj

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1DO9	NMR	-	A	6-99	[»]
2M33	NMR	-	A	1-104	[»]

ProteinModelPortal

P00169.

SMR

P00169. Positions 6-99.

ModBase

Search...

Protein-protein interaction databases

STRING

9986.ENSOCUP00000013951.

Proteomic databases

PRIDE

P00169.

Protocols and materials databases

StructuralBiologyKnowledgebase

Search...

Genome annotation databases

Ensembl

ENSOCUT00000016229; ENSOCUP00000013951; ENSOCUG00000016235.

GeneID

100328912.
100328915.

Phylogenomic databases

eggNOG

COG5274.

GeneTree

ENSGT00510000046507.

HOGENOM

HOG000039853.

HOVERGEN

HBG002653.

OMA

MAEQSDK.

OrthoDB

EOG4S7JRC.

Family and domain databases

Gene3D

3.10.120.10. 1 hit.

InterPro

IPR001199. Cyt_B5-like_heme/steroid-bd.
IPR018506. Cyt_B5_heme-BS.
[Graphical view]

Pfam

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

PRINTS

PR00363. CYTOCHROMEB5.

SUPFAM

SSF55856. Cyt_B5. 1 hit.

PROSITE

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

ProtoNet

Search...

Other

EvolutionaryTrace

P00169.

Entry information

Entry name

CYB5_RABIT

Accession

Primary (citable) accession number: P00169
Secondary accession number(s): Q28726

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 21, 1986
Last sequence update:	January 23, 2007
Last modified:	May 1, 2013
This is version 112 of the entry and version 4 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Chordata Protein Annotation Program