Q4VZI6 (CYB6_CUCSA) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Cytochrome b6

Gene names

Name:	petB
Ordered Locus Names:	CsCp072

Encoded on

Plastid; Chloroplast

Organism

Cucumis sativus (Cucumber)

Taxonomic identifier

3659 [NCBI]

Taxonomic lineage

Eukaryota › Viridiplantae › Streptophyta › Embryophyta › Tracheophyta › Spermatophyta › Magnoliophyta › eudicotyledons › core eudicotyledons › rosids › fabids › Cucurbitales › Cucurbitaceae › Benincaseae › Cucumis

Protein attributes

Sequence length	215 AA.
Sequence status	Complete.
Protein existence	Inferred from homology

General annotation (Comments)

Function	Component of the cytochrome b6-f complex, which mediates electron transfer between photosystem II (PSII) and photosystem I (PSI), cyclic electron flow around PSI, and state transitions By similarity. HAMAP MF_00633
Cofactor	Binds 2 heme groups. One heme group is bound covalently by a single cysteine link, the other one non-covalently By similarity.
Subunit structure	The 4 large subunits of the cytochrome b6-f complex are cytochrome b6, subunit IV (17 kDa polypeptide, petD), cytochrome f and the Rieske protein, while the 4 small subunits are petG, petL, petM and petN. The complex functions as a dimer By similarity.
Subcellular location	Plastid › chloroplast thylakoid membrane; Multi-pass membrane protein By similarity HAMAP MF_00633.
Miscellaneous	Heme 1 (or BH or b566) is high-potential and absorbs at about 566 nm, and heme 2 (or BL or b562) is low-potential and absorbs at about 562 nm By similarity. HAMAP MF_00633
Sequence similarities	Belongs to the cytochrome b family. PetB subfamily.
Sequence caution	The sequence ABI97446.1 differs from that shown. Reason: Erroneous gene model prediction. The proposed translation is equivalent to the unspliced form that is know to occur in some monocots.

Ontologies

Keywords
Biological process	Electron transport Photosynthesis Transport
Cellular component	Chloroplast Membrane Plastid Thylakoid
Domain	Transmembrane Transmembrane helix
Ligand	Heme Iron Metal-binding
Gene Ontology (GO)
Biological process	photosynthesis Inferred from electronic annotation. Source: UniProtKB-KW respiratory electron transport chain Inferred from electronic annotation. Source: InterPro transport Inferred from electronic annotation. Source: UniProtKB-KW
Cellular component	chloroplast thylakoid membrane Inferred from electronic annotation. Source: UniProtKB-SubCell integral to membrane Inferred from electronic annotation. Source: UniProtKB-KW
Molecular function	electron transporter, transferring electrons within cytochrome b6/f complex of photosystem II activity Inferred from electronic annotation. Source: InterPro heme binding Inferred from electronic annotation. Source: InterPro oxidoreductase activity 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 – 215	215	Cytochrome b6 HAMAP MF_00633		PRO_0000275312
Regions
	Transmembrane	32 – 52	21	Helical; Potential
	Transmembrane	90 – 110	21	Helical; Potential
	Transmembrane	116 – 136	21	Helical; Potential
	Transmembrane	186 – 206	21	Helical; Potential
Sites
	Metal binding	86	1	Iron (heme 2 axial ligand) By similarity
	Metal binding	100	1	Iron (heme 1 axial ligand) By similarity
	Metal binding	187	1	Iron (heme 2 axial ligand) By similarity
	Metal binding	202	1	Iron (heme 1 axial ligand) By similarity
	Binding site	35	1	Heme 1 (covalent; via 1 link) By similarity
Experimental info
	Sequence conflict	1 – 2	2	MS → LN in ABI98775. Ref.3

Sequences

	Sequence		Length	Mass (Da)
	Q4VZI6 [UniParc]. Last modified July 5, 2005. Version 1. Checksum: 36539AC417C4D73E	FASTA	215	24,135
	10 20 30 40 50 60 MSKVYDWFEE RLEIQAIADD ITSKYVPPHV NIFYCLGGIT LTCFLVQVAT GFAMTFYYRP 70 80 90 100 110 120 TVTEAFASVQ YIMTEANFGW LIRSVHRWSA SMMVLMMILH VFRVYLTGGF KKPRELTWVT 130 140 150 160 170 180 GVVLAVLTAS FGVTGYSLPR DQIGYWAVKI VTGVPEAIPV IGSPLVELLR GSASVGQSTL 190 200 210 TRFYSLHTFV LPLLTAVFML MHFPMIRKQG ISGPL

References

[1]	"Complete sequence and organization of the cucumber (Cucumis sativus L. cv. Baekmibaekdadagi) chloroplast genome." Kim J.-S., Jung J.D., Lee J.-A., Park H.-W., Oh K.-H., Jeong W.J., Choi D.-W., Liu J.R., Cho K.Y. Plant Cell Rep. 25:334-340(2006) [PubMed: 16362300] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: cv. Baekmibaekdadagi.
[2]	"The complete structure of the cucumber (Cucumis sativus L.) chloroplast genome: its composition and comparative analysis." Plader W.W., Yukawa Y., Sugiura M., Malepszy S. Cell. Mol. Biol. Lett. 12:584-594(2007) [PubMed: 17607527] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: cv. Borszczagowski.
[3]	"Sequencing cucumber (Cucumis sativus L.) chloroplast genomes identifies differences between chilling-tolerant and -susceptible cucumber lines." Chung S.-M., Gordon V.S., Staub J.E. Genome 50:215-225(2007) [PubMed: 17546086] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: cv. Chipper and cv. Gy14.

Cross-references

Sequence databases
EMBL GenBank DDBJ	DQ119058 Genomic DNA. Translation: AAZ94680.1. AJ970307 Genomic DNA. Translation: CAJ00789.1. DQ865975 Genomic DNA. Translation: ABI97446.1. Sequence problems. DQ865976 Genomic DNA. Translation: ABI98775.1.
RefSeq	YP_247630.1. NC_007144.1.
3D structure databases
HSSP	HSSP built from PDB template 1Q90 based on UniProtKB Q00471.
ProteinModelPortal	Q4VZI6.
SMR	Q4VZI6. Positions 4-215.
ModBase	Search...
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Genome annotation databases
GeneID	3429266.
Phylogenomic databases
ProtClustDB	CHL00070.
Family and domain databases
HAMAP	MF_00633. Cytb6_f_cytb6. [Tree]
InterPro	IPR016175. Cyt_b/b6. IPR005797. Cyt_b/b6_N. IPR023530. Cyt_B6_PetB. IPR016174. Di-haem_cyt_TM. [Graphical view]
Gene3D	G3DSA:1.20.810.10. Cytochrome_b/b6. 1 hit.
PANTHER	PTHR19271. Cytochrome_b/b6. 1 hit.
Pfam	PF00033. Cytochrom_B_N. 1 hit. [Graphical view]
PIRSF	PIRSF000032. Cytochrome_b6. 1 hit.
SUPFAM	SSF81342. Transmembr_di-haem_cytochrome. 1 hit.
PROSITE	PS51002. CYTB_NTER. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

CYB6_CUCSA

Accession

Primary (citable) accession number: Q4VZI6
Secondary accession number(s): A5J1W4, A5J247

Entry history

Integrated into UniProtKB/Swiss-Prot:	February 6, 2007
Last sequence update:	July 5, 2005
Last modified:	July 27, 2011
This is version 51 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Plant Protein Annotation Program