Reviewed, UniProtKB/Swiss-Prot P00170 (CYB5_HORSE)

Names and origin

Protein names

Recommended name:
    Cytochrome b5

Gene names

Name:	CYB5A
Synonyms:	CYB5

Organism

Equus caballus (Horse)

Taxonomic identifier

9796 [NCBI]

Taxonomic lineage

Eukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Mammalia › Eutheria › Laurasiatheria › Perissodactyla › Equidae › Equus

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
Domain	Transmembrane
Ligand	Heme Iron Metal-binding
PTM	Acetylation
Technical term	Direct protein sequencing
Gene Ontology (GO)
Biological process	electron transport chain Inferred from electronic annotation. Source: UniProtKB-KW transport 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 microsome Inferred from electronic annotation. Source: UniProtKB-SubCell
Molecular function	heme binding Inferred from electronic annotation. Source: InterPro
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Initiator methionine	1	1	Removed Ref.1 Ref.3
	Chain	2 – 134	133	Cytochrome b5		PRO_0000166009
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
	Modified residue	19	1	N6-acetyllysine By similarity
Experimental info
	Sequence conflict	2 – 6	5	AEQSD → ZEDAS AA sequence Ref.1

Sequences

	Sequence		Length	Mass (Da)
	P00170-1 [UniParc]. Last modified January 23, 2007. Version 3. Checksum: 1CE50847E1F68B21	FASTA	134	15,271
	10 20 30 40 50 60 MAEQSDKAVK YYTLEEIKKH NHSKSTWLIL HHKVYDLTKF LEDHPGGEEV LREQAGGDAT 70 80 90 100 110 120 ENFEDIGHST DARELSKTFI IGELHPDDRS KIAKPVETLI TTVDSNSSWW TNWVIPAISA 130 VVVALMYRIY TAED

References

[1]	"Proteolytic cleavage of horse liver cytochrome b5. Primary structure of the heme-containing moiety." Ozols J., Gerard C., Nobrega F.G. J. Biol. Chem. 251:6767-6774(1976) [PubMed: 977596] [Abstract] Cited for: PROTEIN SEQUENCE OF 2-99.
[2]	"Covalent structure of the membranous segment of horse cytochrome b5. Chemical cleavage of the native hemoprotein." Ozols J., Gerard C. J. Biol. Chem. 252:8549-8553(1977) [PubMed: 562879] [Abstract] Cited for: PROTEIN SEQUENCE OF 90-134.
[3]	"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.

Cross-references

Sequence databases
PIR	CBHO5. S07964.
3D structure databases
HSSP	HSSP built from PDB template 1DO9 based on UniProtKB P00169.
SMR	P00170. Positions 6-99.
ModBase	Search...
Genome annotation databases
Ensembl	ENSECAG00000017581. Equus caballus. [Contig view]
Phylogenomic databases
HOVERGEN	P00170.
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...

Entry information

Entry name

CYB5_HORSE

Accession

Primary (citable) accession number: P00170

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 21, 1986
Last sequence update:	January 23, 2007
Last modified:	June 16, 2009
This is version 77 of the entry and version 3 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

HPI (Human Proteome Initiative)