Reviewed, UniProtKB/Swiss-Prot P83791 (CYB6_MASLA)

Names and origin

Protein names

Recommended name:
    Cytochrome b6

Gene names

Name:

petB

Organism

Mastigocladus laminosus (Fischerella sp.)

Taxonomic identifier

83541 [NCBI]

Taxonomic lineage

Bacteria › Cyanobacteria › Stigonematales › Mastigocladus

Protein attributes

Sequence length	215 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at protein level.

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. HAMAP MF_00633
Cofactor	Binds 2 heme groups. One heme group is bound covalently by a single cysteine link, the other one non-covalently. Ref.1
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. HAMAP MF_00633
Subcellular location	Cellular thylakoid membrane; Multi-pass membrane protein. 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.
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
Technical term	3D-structure
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_0000061827

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) HAMAP MF_00633

Metal binding

100

1

Iron (heme 1 axial ligand) HAMAP MF_00633

Metal binding

187

1

Iron (heme 2 axial ligand) HAMAP MF_00633

Metal binding

202

1

Iron (heme 1 axial ligand) HAMAP MF_00633

Binding site

35

1

Heme 1 (covalent; via 1 link) HAMAP MF_00633

Secondary structure

1

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215

Helix Strand Turn

Details...

Helix

4 – 12

9

Helix

33 – 35

3

Helix

36 – 54

19

Turn

55 – 57

3

Turn

62 – 64

3

Helix

65 – 73

9

Helix

79 – 106

28

Beta strand

109 – 113

5

Helix

116 – 135

20

Turn

136 – 139

4

Helix

142 – 152

11

Helix

154 – 156

3

Helix

161 – 170

10

Beta strand

172 – 175

4

Helix

178 – 188

11

Helix

190 – 204

15

Sequences

	Sequence		Length	Mass (Da)
	P83791-1 [UniParc]. Last modified March 15, 2004. Version 1. Checksum: 4FDCD9336CD31642	FASTA	215	24,227
	10 20 30 40 50 60 MANVYDWFQE RLEIQALADD VTSKYVPPHV NIFYCLGGIT LTCFLIQFAT GFAMTFYYKP 70 80 90 100 110 120 TVTEAYASVQ YIMNEVSFGW LIRSIHRWSA SMMVLMMILH VFRVYLTGGF KKPRELTWIS 130 140 150 160 170 180 GVILAVITVS FGVTGYSLPW DQVGYWAVKI VSGVPEAIPV VGVLISDLLR GGSSVGQATL 190 200 210 TRYYSAHTFV LPWLIAVFML LHFLMIRKQG ISGPL

References

[1]	"Full subunit coverage liquid chromatography electrospray ionization mass spectrometry (LCMS+) of an oligomeric membrane protein: cytochrome b(6)f complex from spinach and the cyanobacterium Mastigocladus laminosus." Whitelegge J.P., Zhang H., Aguilera R., Taylor R.M., Cramer W.A. Mol. Cell. Proteomics 1:816-827(2002) [PubMed: 12438564] [Abstract] Cited for: HEME-BINDING.
[2]	"Structure of the cytochrome b6f complex of oxygenic photosynthesis: tuning the cavity." Kurisu G., Zhang H., Smith J.L., Cramer W.A. Science 302:1009-1014(2003) [PubMed: 14526088] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (3.0 ANGSTROMS), METAL-BINDING SITES.
+	Additional computationally mapped references.

Cross-references

3D structure databases

PDBPDBe

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1VF5	X-ray	3.00	A/N	1-215	[»]
2D2C	X-ray	3.80	A/N	1-215	[»]
2E74	X-ray	3.00	A	1-215	[»]
2E75	X-ray	3.55	A	1-215	[»]
2E76	X-ray	3.41	A	1-215	[»]

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_MASLA

Accession

Primary (citable) accession number: P83791

Entry history

Integrated into UniProtKB/Swiss-Prot:	April 13, 2004
Last sequence update:	March 15, 2004
Last modified:	March 3, 2009
This is version 42 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)