Q71KN3 (CYB6_KLEBI) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Cytochrome b6

Gene names

Name:

petB

Encoded on

Plastid; Chloroplast

Organism

Klebsormidium bilatum (Filamentous green alga)

Taxonomic identifier

201239 [NCBI]

Taxonomic lineage

Eukaryota › Viridiplantae › Streptophyta › Klebsormidiophyceae › Klebsormidiales › Klebsormidiaceae › Klebsormidium

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.

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_0000061799
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

Sequences

	Sequence		Length	Mass (Da)
	Q71KN3 [UniParc]. Last modified July 5, 2004. Version 1. Checksum: 74C807E3315DE5A2	FASTA	215	24,207
	10 20 30 40 50 60 MGKVYDWFEE RLEIQAIADD VTSKYVPPHV NIFYCLGGIT LTCFLVQVAT GFAMTFYYRP 70 80 90 100 110 120 TVTEAFASVQ YLMTDVNFGW LIRSVHRWSA SMMVLMMILH VFRVYLTGGF KKPRELTWVT 130 140 150 160 170 180 GVILAVLTVS FGVTGYSLPW DQVGYWAVKI VTGVPEAIPV IGSPLVELLR GSVSVGQSTL 190 200 210 TRFYSLHTFV LPLLTAVFML MHFLMIRKQG ISGPL

References

[1]	"psbB gene cluster in Charophyceae." Lee J., Manhart J.R. Submitted (FEB-2002) to the EMBL/GenBank/DDBJ databases Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].

Cross-references

Sequence databases
EMBL GenBank DDBJ	AF482500 Genomic DNA. Translation: AAQ05925.1.
3D structure databases
ProteinModelPortal	Q71KN3.
SMR	Q71KN3. Positions 4-215.
ModBase	Search...
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
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_KLEBI

Accession

Primary (citable) accession number: Q71KN3

Entry history

Integrated into UniProtKB/Swiss-Prot:	March 15, 2005
Last sequence update:	July 5, 2004
Last modified:	July 27, 2011
This is version 45 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Plant Protein Annotation Program