Reviewed, UniProtKB/Swiss-Prot P00172 (CYB5_PIG)

Names and origin

Protein names

Recommended name:
    Cytochrome b5

Gene names

Name:	CYB5A
Synonyms:	CYB5

Organism

Sus scrofa (Pig)

Taxonomic identifier

9823 [NCBI]

Taxonomic lineage

Eukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Mammalia › Eutheria › Laurasiatheria › Cetartiodactyla › Suina › Suidae › Sus

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	Isoform 1: Endoplasmic reticulum membrane; Single-pass membrane protein; Cytoplasmic side. Microsome membrane; Single-pass membrane protein; Cytoplasmic side. Isoform 2: Cytoplasm.
Sequence similarities	Belongs to the cytochrome b5 family. Contains 1 cytochrome b5 heme-binding domain.

Ontologies

Keywords
Biological process	Electron transport Transport
Cellular component	Cytoplasm Endoplasmic reticulum Membrane Microsome
Coding sequence diversity	Alternative splicing
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...

Alternative products

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

Isoform 1 (identifier: P00172-1)

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: P00172-2)

Also known as: Erythrocyte; Cytoplasmic;

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

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Initiator methionine	1	1	Removed Ref.2 Ref.3 Ref.6
	Chain	2 – 134	133	Cytochrome b5		PRO_0000166012
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
Natural variations
	Alternative sequence	98	1	T → S in isoform 2.		VSP_001242
	Alternative sequence	99 – 134	36	Missing in isoform 2.		VSP_001243
Experimental info
	Sequence conflict	62	1	N → D AA sequence Ref.4

Sequences

	Sequence		Length	Mass (Da)
	Isoform 1 (Liver) (Membrane-bound) [UniParc]. Last modified January 23, 2007. Version 3. Checksum: 016FE14A32CAC52A	FASTA	134	15,310
	10 20 30 40 50 60 MAEQSDKAVK YYTLEEIQKH NNSKSTWLIL HHKVYDLTKF LEEHPGGEEV LREQAGGDAT 70 80 90 100 110 120 ENFEDVGHST DARELSKTFI IGELHPDDRS KIAKPSETLI TTVESNSSWW TNWVIPAISA 130 LVVSLMYHFY TSEN
	Isoform 2 (Erythrocyte) (Cytoplasmic). Checksum: 0486B7929253106B	FASTA	98	11,153
	10 20 30 40 50 60 MAEQSDKAVK YYTLEEIQKH NNSKSTWLIL HHKVYDLTKF LEEHPGGEEV LREQAGGDAT 70 80 90 ENFEDVGHST DARELSKTFI IGELHPDDRS KIAKPSES

References

[1]	"The isolation and characterization of the soluble and membrane-bound porcine cytochrome b5 cDNAs." Vandermark P.K., Steggles A.W. Biochem. Biophys. Res. Commun. 240:80-83(1997) [PubMed: 9367886] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORMS 1 AND 2). Tissue: Blood and Liver.
[2]	"Amino acid sequences of cytochrome b5 from human, porcine, and bovine erythrocytes and comparison with liver microsomal cytochrome b5." Abe K., Kimura S., Kizawa R., Anan F.K., Sugita Y. J. Biochem. 97:1659-1668(1985) [PubMed: 4030743] [Abstract] Cited for: PROTEIN SEQUENCE OF 2-134. Tissue: Erythrocyte and Liver.
[3]	"Cytochrome b5 from microsomal membranes of equine, bovine, and porcine livers. Isolation and properties of preparations containing the membranous segment." Ozols J. Biochemistry 13:426-434(1974) [PubMed: 4810060] [Abstract] Cited for: PROTEIN SEQUENCE OF 2-7.
[4]	"Amino acid sequences of tryptic peptides of cytochromes b5 from microsomes of human, monkey, porcine, and chicken liver." Nobrega F.G., Ozols J. J. Biol. Chem. 246:1706-1717(1971) [PubMed: 4993957] [Abstract] Cited for: PROTEIN SEQUENCE OF 8-89.
[5]	"Primary structure of the membranous segment of cytochrome b5." Ozols J., Gerard C. Proc. Natl. Acad. Sci. U.S.A. 74:3725-3729(1977) [PubMed: 269425] [Abstract] Cited for: PROTEIN SEQUENCE OF 90-134, SEQUENCE REVISION TO 14; 15 AND 61.
[6]	"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
EMBLGenBankDDBJ	AF016388 mRNA. Translation: AAC48779.1. AF016389 mRNA. Translation: AAC48780.1.
PIR	CBPG5. JC5782. JC5783.
RefSeq	NP_001001770.1.
UniGene	Ssc.12198
3D structure databases
HSSP	HSSP built from PDB template 1CYO based on UniProtKB P00171.
SMR	P00172. Positions 7-92.
ModBase	Search...
Genome annotation databases
GeneID	414799.
KEGG	ssc:414799.
Phylogenomic databases
HOVERGEN	P00172.
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_PIG

Accession

Primary (citable) accession number: P00172
Secondary accession number(s): O18813

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 21, 1986
Last sequence update:	January 23, 2007
Last modified:	June 16, 2009
This is version 84 of the entry and version 3 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

HPI (Human Proteome Initiative)