Reviewed, UniProtKB/Swiss-Prot P05642 (CYB6_MAIZE)

Names and origin

Protein names

Recommended name:
    Cytochrome b6

Gene names

Name:

petB

Encoded on

Plastid; Chloroplast

Organism

Zea mays (Maize)

Taxonomic identifier

4577 [NCBI]

Taxonomic lineage

Eukaryota › Viridiplantae › Streptophyta › Embryophyta › Tracheophyta › Spermatophyta › Magnoliophyta › Liliopsida › Poales › Poaceae › PACCAD clade › Panicoideae › Andropogoneae › Zea

Protein attributes

Sequence length	215 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at transcript 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 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.
RNA editing	Edited at position 204. Editing is independent of both splicing and processing of the primary transcript. Ref.2

Ontologies

Keywords
Biological process	Electron transport Photosynthesis Transport
Cellular component	Chloroplast Membrane Plastid Thylakoid
Coding sequence diversity	Alternative splicing RNA editing
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...

Alternative products

This entry describes 2 isoforms produced by alternative splicing. [Align] [Select]

Isoform 1 (identifier: P05642-1)

This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.

Isoform 2 (identifier: P05642-2)

The sequence of this isoform differs from the canonical sequence as follows:
     1-2: MS → MKFSYTVLGGGVGLVTYLN

Note: Unspliced isoform.

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_0000061801
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
Natural variations
	Alternative sequence	1 – 2	2	MS → MKFSYTVLGGGVGLVTYLN in isoform 2. HAMAP MF_00633		VSP_007116

Sequences

	Sequence		Length	Mass (Da)
	Isoform 1 [UniParc]. Last modified November 28, 2003. Version 2. Checksum: C2E389FA11B51F6A	FASTA	215	24,197
	10 20 30 40 50 60 MSKVYDWFEE RLEIQAIADD ITSKYVPPHV NIFYCLGGIT LTCFLVQVAT GFAMTFYYRP 70 80 90 100 110 120 TVTEAFSSVQ YIMTEANFGW LIRSVHRWSA SMMVLMMILH VFRVYLTGGF KKPRELTWVT 130 140 150 160 170 180 GVVLAVLTAS FGVTGYSLPW DQIGYWAVKI VTGVPEAIPV IGSPLVELLR GSASVGQSTL 190 200 210 TRFYSLHTFV LPLLTAVFML MHFLMIRKQG ISGPL
	Isoform 2. Checksum: FB6868A5216A880A	FASTA	232	25,980
	10 20 30 40 50 60 MKFSYTVLGG GVGLVTYLNK VYDWFEERLE IQAIADDITS KYVPPHVNIF YCLGGITLTC 70 80 90 100 110 120 FLVQVATGFA MTFYYRPTVT EAFSSVQYIM TEANFGWLIR SVHRWSASMM VLMMILHVFR 130 140 150 160 170 180 VYLTGGFKKP RELTWVTGVV LAVLTASFGV TGYSLPWDQI GYWAVKIVTG VPEAIPVIGS 190 200 210 220 230 PLVELLRGSA SVGQSTLTRF YSLHTFVLPL LTAVFMLMHF LMIRKQGISG PL

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"The maize plastid psbB-psbF-petB-petD gene cluster: spliced and unspliced petB and petD RNAs encode alternative products." Rock C.D., Barkan A., Taylor W.C. Curr. Genet. 12:69-77(1987) [PubMed: 2835175] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] (ISOFORMS 1 AND 2).
[2]	"RNA editing in maize chloroplasts is a processing step independent of splicing and cleavage to monocistronic mRNAs." Freyer R., Hoch B., Neckermann K., Maier R.M., Koessel H. Plant J. 4:621-629(1993) [PubMed: 8252066] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA] (ISOFORM 1), RNA EDITING. Tissue: Seedling.
[3]	"Complete sequence of the maize chloroplast genome: gene content, hotspots of divergence and fine tuning of genetic information by transcript editing." Maier R.M., Neckermann K., Igloi G.L., Koessel H. J. Mol. Biol. 251:614-628(1995) [PubMed: 7666415] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].

Cross-references

Sequence databases
EMBLGenBankDDBJ	X05422 Genomic DNA. Translation: CAA28999.1. Sequence problems. X05422 Genomic DNA. Translation: CAA29000.1. Sequence problems. S67283, S67282 Genomic DNA. Translation: AAB29194.1. X86563 Genomic DNA. Translation: CAA60315.1. Sequence problems.
PIR	CBZM6R. S08592. S58581.
RefSeq	NP_043053.1.
3D structure databases
SMR	P05642. Positions 4-215.
ModBase	Search...
Genome annotation databases
GeneID	845192.
Organism-specific databases
Gramene	P05642.
MaizeGDB	56334.
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_MAIZE

Accession

Primary (citable) accession number: P05642
Secondary accession number(s): Q33298, Q36712

Entry history

Integrated into UniProtKB/Swiss-Prot:	November 1, 1988
Last sequence update:	November 28, 2003
Last modified:	June 16, 2009
This is version 72 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

HAMAP (High-quality Automated and Manual Annotation of microbial Proteomes)