Reviewed, UniProtKB/Swiss-Prot P12122 (CYB6_NOSSP)

Names and origin

Protein names

Recommended name:
    Cytochrome b6

Gene names

Name:

petB

Organism

Nostoc sp. (strain PCC 7906)

Taxonomic identifier

1181 [NCBI]

Taxonomic lineage

Bacteria › Cyanobacteria › Nostocales › Nostocaceae › Nostoc

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	Cellular 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	Membrane 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	integral to membrane Inferred from electronic annotation. Source: UniProtKB-KW thylakoid membrane Inferred from electronic annotation. Source: UniProtKB-SubCell
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_0000061828
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)
	P12122-1 [UniParc]. Last modified October 1, 1989. Version 1. Checksum: A0CE8C6FC654C38E	FASTA	215	24,260
	10 20 30 40 50 60 MANVYDWFEE RLEIQAIAED VTSKYVPPHV NIFYCLGGIT LTCFLIQFAT GFAMTFYYKP 70 80 90 100 110 120 TVAEAFSSVE YIMNEVNFGW LIRSIHRWSA SMMVLMMILH VFRVYLTGGF KKPRELTWVS 130 140 150 160 170 180 GVILAVITVS FGVTGYSLPW DQVGYWAVKI VSGVPEAIPV VGVLISDLLR GGSSVGQATL 190 200 210 TRYYSAHTFV LPWLIAVFML FHFLMIRKQG ISGPL

References

[1]

"Characterization of two operons encoding the cytochrome b6-f complex of the cyanobacterium Nostoc PCC 7906. Highly conserved sequences but different gene organization than in chloroplasts." Kallas T., Spiller S., Malkin R. J. Biol. Chem. 263:14334-14342(1988) [PubMed: 2844767] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].

Cross-references

Sequence databases
EMBLGenBankDDBJ	J03967 Genomic DNA. Translation: AAA23330.1.
PIR	A30807.
3D structure databases
SMR	P12122. Positions 13-214.
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_NOSSP

Accession

Primary (citable) accession number: P12122

Entry history

Integrated into UniProtKB/Swiss-Prot:	October 1, 1989
Last sequence update:	October 1, 1989
Last modified:	March 3, 2009
This is version 59 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)