HAMAP

Accession	MF_00633
Dates	4-APR-2003 (Created) 2-DEC-2010 (Last updated, Version 46)

Data class

Protein

Predictors

HAMAP; MF_00633; [distribution of match scores in UniProtKB];[seed alignment for MF_00633]

Names

Cytb6_f_cytb6

Identifier

CYB6

Protein name

RecName: Full=Cytochrome b6;

Gene name

petB

Gene name

petB, cytB

FUNCTION: Component of the cytochrome bc complex which donates electrons to the photosynthetic reaction center (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: The subunits of the cytochrome bc complex are a Rieske Fe-S protein (PetC), cytochrome b6 (PetB), subunit IV (PetD), and a diheme cytochrome c (PetX) (By similarity).

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: 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: Cell membrane; Multi-pass membrane protein (By similarity).

SUBCELLULAR LOCATION: Plastid, chloroplast thylakoid membrane; Multi-pass membrane protein (By similarity).

SUBCELLULAR LOCATION: Cell inner membrane; Multi-pass membrane protein (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).

SIMILARITY: Belongs to the cytochrome b family. PetB subfamily.

Pfam	PF00033; Cytochrom_B_N; 1;
PROSITE	PS51002; CYTB_NTER; 1;

Transport, Electron transport, Photosynthesis.

Cell membrane, Cell inner membrane.

Thylakoid.

Cell membrane.

Membrane, Heme, Metal-binding, Iron, Transmembrane, Transmembrane helix.

GO:0005886; Cellular component: plasma membrane.

GO:0009535; Cellular component: chloroplast thylakoid membrane.

GO:0042651; Cellular component: thylakoid membrane.

GO:0045158; Molecular function: electron transporter, transferring electrons within cytochrome b6/f complex of photosystem II activity.
GO:0015979; Biological process: photosynthesis.
GO:0055114; Biological process: oxidation-reduction process.

From: CYB6_ARATH (P56773)
Key		From		To		Description		Condition		FTGroup
TRANSMEM		32		52		Helical; (Potential)
TRANSMEM		90		110		Helical; (Potential)
TRANSMEM		116		136		Helical; (Potential)
TRANSMEM		186		206		Helical; (Potential)
METAL		86		86		Iron (heme 2 axial ligand) (By similarity)		H
METAL		100		100		Iron (heme 1 axial ligand) (By similarity)		H
METAL		187		187		Iron (heme 2 axial ligand) (By similarity)		H
METAL		202		202		Iron (heme 1 axial ligand) (By similarity)		H
BINDING		35		35		Heme 1 (covalent; via 1 link) (By similarity)		C

Size range:	213-222 amino acids
Related UniRules:	None
Template:	Q00471 (CYB6_CHLRE); P00165 (CYB6_SPIOL): [Recover all]
Scope:	Bacteria; Cyanobacteria Bacteria; Heliobacteriaceae Plastid
Fusion:	Nter: None; Cter: None
Duplicate:	None
Plasmid encoded:	None
Comments:	In maize and tobacco position 204 has been shown to undergo RNA editing to change the codon from Pro to Leu. It has therefore been suggested to occur in all other plants where this codon is Pro (CCA -> CTA). In C.reinhardtii an engineered Pro mutation at this position is unable to assemble intact complex, giving strength to this suggestion.