P49099 (CYB5S_TOBAC) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names	Recommended name: Cytochrome b5, seed isoform
Organism	Nicotiana tabacum (Common tobacco)
Taxonomic identifier	4097 [NCBI]
Taxonomic lineage	Eukaryota › Viridiplantae › Streptophyta › Embryophyta › Tracheophyta › Spermatophyta › Magnoliophyta › eudicotyledons › core eudicotyledons › asterids › lamiids › Solanales › Solanaceae › Nicotianoideae › Nicotianeae › Nicotiana

Protein attributes

Sequence length	135 AA.
Sequence status	Complete.
Protein existence	Evidence at transcript level

General annotation (Comments)

Function	Cytochrome b5 is a membrane bound hemoprotein which function as an electron carrier for several membrane bound oxygenases. May play a key role in the modification by desaturation of fatty acids in the endoplasmic reticulum, which in the developing seed is utilized for membrane synthesis and in the developmentally regulated production of large amounts of storage lipids.
Subcellular location	Endoplasmic reticulum membrane; Single-pass membrane protein; Cytoplasmic side By similarity. Microsome membrane; Single-pass membrane protein; Cytoplasmic side By similarity.
Tissue specificity	Specifically expressed in developing seeds.
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 Transmembrane helix
Ligand	Heme Iron Metal-binding
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
	Chain	1 – 135	135	Cytochrome b5, seed isoform		PRO_0000166026
Regions
	Transmembrane	107 – 127	21	Helical; Potential
	Domain	5 – 81	77	Cytochrome b5 heme-binding
Sites
	Metal binding	40	1	Iron (heme axial ligand) By similarity
	Metal binding	64	1	Iron (heme axial ligand) By similarity

Sequences

	Sequence		Length	Mass (Da)
	P49099 [UniParc]. Last modified February 1, 1996. Version 1. Checksum: A36CCA081A72ECBC	FASTA	135	14,869
	10 20 30 40 50 60 MGGQSKVFTL AEVSNHNNAK DCWLIISGKV YNVTKFLEDH PGGGEVLLSA TGKDATDDFE 70 80 90 100 110 120 DIGHSSSARA MLDEYYVGDI DSSTIPTKVK YTPPKQPHYN QDKTTEFIVK LLQFLVPLII 130 LGVAFGVHFY TKQSA

References

[1]	"Isolation of a cDNA encoding a cytochrome b5 specifically expressed in developing tobacco seeds." Napier J.A., Smith M.A., Stobart A.K., Shewry P.R. Planta 197:200-202(1995) [PubMed: 7580860] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA]. Strain: cv. Samsun. Tissue: Seed.
+	Additional computationally mapped references.

Cross-references

Sequence databases
EMBL GenBank DDBJ	X80008 mRNA. Translation: CAA56318.1.
PIR	S49200.
3D structure databases
ProteinModelPortal	P49099.
ModBase	Search...
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
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.
SUPFAM	SSF55856. Cyt_B5. 1 hit.
PROSITE	PS00191. CYTOCHROME_B5_1. 1 hit. PS50255. CYTOCHROME_B5_2. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

CYB5S_TOBAC

Accession

Primary (citable) accession number: P49099

Entry history

Integrated into UniProtKB/Swiss-Prot:	February 1, 1996
Last sequence update:	February 1, 1996
Last modified:	September 21, 2011
This is version 72 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Plant Protein Annotation Program