Reviewed, UniProtKB/Swiss-Prot Q9XQU7 (CYB6_HETTR)

Names and origin

Protein names

Recommended name:
    Cytochrome b6

Gene names

Name:	petB
Synonyms:	cytB

Encoded on

Plastid; Chloroplast

Organism

Heterocapsa triquetra (Dinoflagellate)

Taxonomic identifier

66468 [NCBI]

Taxonomic lineage

Eukaryota › Alveolata › Dinophyceae › Peridiniales › Heterocapsaceae › Heterocapsa

Protein attributes

Sequence length	219 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 › chloroplast 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	Chloroplast 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	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: 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 – 219	219	Cytochrome b6 HAMAP MF_00633		PRO_0000061796
Regions
	Transmembrane	32 – 52	21	Potential
	Transmembrane	90 – 110	21	Potential
	Transmembrane	116 – 136	21	Potential
	Transmembrane	190 – 210	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	191	1	Iron (heme 2 axial ligand) By similarity
	Metal binding	206	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)
	Q9XQU7-1 [UniParc]. Last modified November 1, 1999. Version 1. Checksum: 86278EC45E962D79	FASTA	219	24,373
	10 20 30 40 50 60 MGFIYDWSEE RLEIQSIADD ILSKFVPSHV NIFYCFGGIV LTAFIFQGAS GFALTIYYRP 70 80 90 100 110 120 TVVEAFSSIQ LILYHVNLGW FIRSIHRWSS GCMVLVLILH ISRVYLTGGF KKPRELTWIS 130 140 150 160 170 180 GVILAVVTVS FGVTGYSLPW DQIGYWACKI VTAVPEALDD LLPGAGKLLV LTLRGGFSVG 190 200 210 QTTLTRLYSI HTFVLPLVTL VLLIVHFSLL RKQGISGPL

References

[1]	"Single gene circles in dinoflagellate chloroplast genomes." Zhang Z., Green B.R., Cavalier-Smith T. Nature 400:155-159(1999) [PubMed: 10408440] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA]. Strain: CCMP449.

Cross-references

Sequence databases
EMBLGenBankDDBJ	AF130037 Genomic DNA. Translation: AAD44704.1.
3D structure databases
ModBase	Search...
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_HETTR

Accession

Primary (citable) accession number: Q9XQU7

Entry history

Integrated into UniProtKB/Swiss-Prot:	April 11, 2003
Last sequence update:	November 1, 1999
Last modified:	June 16, 2009
This is version 48 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)