Reviewed, UniProtKB/Swiss-Prot P48121 (CYB6_CYAPA)

Names and origin

Protein names

Recommended name:
    Cytochrome b6

Gene names

Name:

petB

Encoded on

Plastid; Cyanelle

Organism

Cyanophora paradoxa

Taxonomic identifier

2762 [NCBI]

Taxonomic lineage

Eukaryota › Glaucocystophyceae › Cyanophoraceae › Cyanophora

Protein attributes

Sequence length	215 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
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.
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 › cyanelle thylakoid membrane; Multi-pass membrane protein By similarity.
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.
Sequence similarities	Belongs to the cytochrome b family. PetB subfamily.

Ontologies

Keywords
Biological process	Electron transport Photosynthesis Transport
Cellular component	Cyanelle Membrane Plastid Thylakoid
Domain	Transmembrane
Ligand	Heme Iron Metal-binding
Gene Ontology (GO)
Biological process	photosynthesis Inferred from electronic annotation. Source: HAMAP respiratory electron transport chain Inferred from electronic annotation. Source: InterPro transport Inferred from electronic annotation. Source: UniProtKB-KW
Cellular component	cyanelle 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: HAMAP iron ion binding Inferred from electronic annotation. Source: UniProtKB-KW 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_0000061792
Regions
	Transmembrane	32 – 52	21	Potential
	Transmembrane	90 – 110	21	Potential
	Transmembrane	116 – 136	21	Potential
	Transmembrane	186 – 206	21	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

Sequences

	Sequence		Length	Mass (Da)
	P48121-1 [UniParc]. Last modified February 1, 1996. Version 1. Checksum: B640C8B9421E2B2A	FASTA	215	24,189
	10 20 30 40 50 60 MSKVYDWFQE RLEIQAIADD ITSKYVPPHV NIFYCLGGIT LTCFLVQVAT GFAMTFYYRP 70 80 90 100 110 120 TVTEAFASVQ YIMTDVNFGW LIRSTHRWSA SMMVLMMILH VFRVYLTGGF KKPRELTWVV 130 140 150 160 170 180 GVILAVITVS FGVTGYSLPW DQVGYWAVKI VTGVPEAIPV IGSNVVELLR GSVSVGQSTL 190 200 210 TRFYSLHTFV LPLLSAVFML VHFLLIRKQG ISGPL

References

[1]

"Nucleotide sequence of the cyanelle DNA from Cyanophora paradoxa." Stirewalt V.L., Michalowski C.B., Loeffelhardt W., Bohnert H.J., Bryant D.A. Plant Mol. Biol. Rep. 13:327-332(1995) Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: UTEX LB 555 / Pringsheim.

[2]

"The complete sequence of the cyanelle genome of Cyanophora paradoxa: the genetic complexity of a primitive plastid." Loeffelhardt W., Stirewalt V.L., Michalowski C.B., Annarella M., Farley J.Y., Schluchter W.M., Chung S., Newmann-Spallart C., Steiner J.M., Jakowitsch J., Bohnert H.J., Bryant D.A. (In) Schenk H.E.A., Herrmann R., Jeon K.W., Mueller N.E., Schwemmler W. (eds.); Eukaryotism and symbiosis, pp.40-48, Springer-Verlag, Heidelberg (1997) Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA]. Strain: UTEX LB 555 / Pringsheim.

Cross-references

Sequence databases
EMBLGenBankDDBJ	U30821 Genomic DNA. Translation: AAA81206.1.
PIR	T06863.
RefSeq	NP_043175.1.
3D structure databases
SMR	P48121. Positions 4-215.
ModBase	Search...
Genome annotation databases
GeneID	801518.
Family and domain databases
HAMAP	MF_00633. [Tree]
InterPro	IPR016175. Cyt_b/b6. IPR005797. Cyt_b/b6_N. [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]
PROSITE	PS51002. CYTB_NTER. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

CYB6_CYAPA

Accession

Primary (citable) accession number: P48121

Entry history

Integrated into UniProtKB/Swiss-Prot:	February 1, 1996
Last sequence update:	February 1, 1996
Last modified:	June 16, 2009
This is version 55 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

HAMAP (High-quality Automated and Manual Annotation of microbial Proteomes)