9W2X: Cytochrome b-c1 complex subunit 1, mitochondrial

Cryo-EM structure of complex III on the bovine heart submitochondrial particles, III-1. Determined by electron microscopy at 2.2 Å resolution. Released 1 Apr 2026.

Method: Electron microscopy
Resolution: 2.2 Å
Organism: Bos taurus
Chains: 22
Atoms: 33,248
Mol. weight: 474.08 kDa
Ligands: HEM, HEC, FES
Released: 1 Apr 2026

Explore 9W2X in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9W2X contains 236 α-helices and 126 β-strands across 22 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 25 helices, 14 β-strands

Element	Residues	Length	Sheet
α-helix	4-9	6
α-helix	12-14	3
β-strand	15-18	4	1
β-strand	24-29	6	1
β-strand	34-41	8	1
α-helix	45-47	3
α-helix	55-62	8
β-strand	67	1	2
α-helix	72-82	11
β-strand	85-90	6	1
β-strand	95-102	8	1
α-helix	103-105	3
α-helix	106-118	13
β-strand	120	1	2
α-helix	124-141	18
α-helix	145-157	13
α-helix	162-164	3
α-helix	171-176	6
α-helix	179-189	11
α-helix	192-194	3
β-strand	195-201	7	1
α-helix	205-215	11
α-helix	224-226	3
β-strand	239-244	6	3
β-strand	251-258	8	3
α-helix	267-277	11
β-strand	280-281	2	3
α-helix	287-289	3
α-helix	293-301	9
β-strand	306-314	9	3
β-strand	317-326	10	3
α-helix	331-347	17
α-helix	351-368	18
α-helix	372-385	14
α-helix	392-400	9
α-helix	404-415	12
β-strand	421-426	6	3
α-helix	432-433	2
α-helix	434-439	6

Chain B: 22 helices, 18 β-strands

Element	Residues	Length	Sheet
β-strand	25-28	4	4
β-strand	34-38	5	4
β-strand	44-51	8	4
α-helix	55-57	3
α-helix	65-71	7
β-strand	77	1	5
α-helix	82-92	11
β-strand	95-100	6	4
β-strand	105-112	8	4
α-helix	116-128	13
β-strand	130	1	5
α-helix	134-140	7
α-helix	143-151	9
α-helix	155-167	13
β-strand	168	1	6
α-helix	180-182	3
α-helix	188-198	11
α-helix	201-203	3
β-strand	204-209	6	4
α-helix	213-223	11
α-helix	236-237	2
β-strand	239	1	6
β-strand	243-244	2	7
β-strand	247	1	8
β-strand	252-260	9	7
α-helix	262-263	2
α-helix	267-279	13
β-strand	285	1	1
α-helix	294-300	7
β-strand	308-315	8	7
β-strand	320-329	10	7
α-helix	333-348	16
α-helix	354-370	17
α-helix	375-388	14
α-helix	395-403	9
α-helix	407-418	12
β-strand	422-427	6	7
β-strand	428	1	8
α-helix	433-435	3
α-helix	436-438	3

Chain C: 22 helices, 4 β-strands

Element	Residues	Length	Sheet
α-helix	4-7	4
α-helix	9-18	10
β-strand	22-24	3	9
α-helix	29-31	3
α-helix	33-52	20
α-helix	62-71	10
α-helix	76-103	28
α-helix	106-108	3
α-helix	110-131	22
β-strand	136	1	10
α-helix	137-147	11
α-helix	148-152	5
α-helix	157-165	9
α-helix	172-200	29
β-strand	217-219	3	9
α-helix	223-245	23
α-helix	253-256	4
β-strand	258	1	10
α-helix	272-281	10
α-helix	287-303	17
α-helix	304-307	4
α-helix	315-317	3
α-helix	319-339	21
α-helix	345-360	16
α-helix	361-365	5
α-helix	366-376	11

Chain D: 11 helices, 11 β-strands

Element	Residues	Length	Sheet
α-helix	23-35	13
α-helix	37-39	3
β-strand	42	1	11
β-strand	47	1	12
α-helix	48-51	4
β-strand	52	1	13
β-strand	56	1	13
α-helix	58-66	9
β-strand	69-72	4	14
β-strand	81-84	4	14
α-helix	89	1
β-strand	90	1	12
α-helix	91-93	3
α-helix	98-103	6
α-helix	110-111	2
β-strand	112	1	11
α-helix	124-131	8
β-strand	148	1	15
β-strand	158	1	15
α-helix	179-194	16
α-helix	198-231	34
β-strand	234-237	4	3

Chain E: 11 helices, 13 β-strands

Element	Residues	Length	Sheet
α-helix	2-4	3
α-helix	7-9	3
β-strand	14	1	16
α-helix	16-18	3
α-helix	25-27	3
α-helix	29-60	32
α-helix	66-69	4
β-strand	74-77	4	17
α-helix	78-80	3
β-strand	86-91	6	18
β-strand	94-99	6	18
α-helix	100-102	3
α-helix	103-110	8
α-helix	123-125	3
β-strand	129	1	19
β-strand	132	1	19
β-strand	133-136	4	18
β-strand	147-148	2	20
β-strand	156-158	3	20
β-strand	163-165	3	20
β-strand	171-173	3	20
α-helix	179-181	3
β-strand	185-189	5	17
β-strand	192-195	4	17

Chain F: 8 helices, 0 β-strands

Element	Residues	Length
α-helix	8-24	17
α-helix	26-29	4
α-helix	33-36	4
α-helix	41-48	8
α-helix	52-70	19
α-helix	77-79	3
α-helix	81-82	2
α-helix	91-109	19

Chain G: 3 helices, 2 β-strands

Element	Residues	Length	Sheet
β-strand	13-18	6	3
β-strand	23	1	16
α-helix	29-42	14
α-helix	45-69	25
α-helix	74-77	4

Chain H: 4 helices, 0 β-strands

Element	Residues	Length
α-helix	16-25	10
α-helix	28-46	19
α-helix	55-72	18
α-helix	73-76	4

14 more chain groups are not listed. Open the entry in the viewer and use the sequence panel to see them.

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Cytochrome b-c1 complex subunit 1, mitochondrial	A, N	protein	446	Bos taurus	P31800 (AlphaFold model)
Cytochrome b-c1 complex subunit 2, mitochondrial	B, O	protein	425	Bos taurus	P23004 (AlphaFold model)
Cytochrome b	C, P	protein	378	Bos taurus	P00157 (AlphaFold model)
Cytochrome c1, heme protein, mitochondrial	D, Q	protein	241	Bos taurus	P00125 (AlphaFold model)
Cytochrome b-c1 complex subunit Rieske, mitochondrial	E, R	protein	196	Bos taurus	P13272
Cytochrome b-c1 complex subunit 7	F, S	protein	105	Bos taurus	P00129
Cytochrome b-c1 complex subunit 8	G, T	protein	80	Bos taurus	P13271
Cytochrome b-c1 complex subunit 6, mitochondrial	H, U	protein	67	Bos taurus	P00126
Cytochrome b-c1 complex subunit 9	I, V	protein	57	Bos taurus	P13272
Cytochrome b-c1 complex subunit 9	J, W	protein	61	Bos taurus	P00130
Cytochrome b-c1 complex subunit 10	K, X	protein	52	Bos taurus	P07552

Sequence of entity 1 (A, N), FASTA

>9W2X_1 Cytochrome b-c1 complex subunit 1, mitochondrial (chains A, N)
TATYAQALQSVPETQVSQLDNGLRVASEQSSQPTCTVGVWIDAGSRYESEKNNGAGYFVE
HLAFKGTKNRPGNALEKEVESMGAHLNAYSTREHTAYYIKALSKDLPKAVELLADIVQNC
SLEDSQIEKERDVILQELQENDTSMRDVVFNYLHATAFQGTPLAQSVEGPSENVRKLSRA
DLTEYLSRHYKAPRMVLAAAGGLEHRQLLDLAQKHFSGLSGTYDEDAVPTLSPCRFTGSQ
ICHREDGLPLAHVAIAVEGPGWAHPDNVALQVANAIIGHYDCTYGGGAHLSSPLASIAAT
NKLCQSFQTFNICYADTGLLGAHFVCDHMSIDDMMFVLQGQWMRLCTSATESEVLRGKNL
LRNALVSHLDGTTPVCEDIGRSLLTYGRRIPLAEWESRIAEVDARVVREVCSKYFYDQCP
AVAGFGPIEQLPDYNRIRSGMFWLRF

Sequence of entity 2 (B, O), FASTA

>9W2X_2 Cytochrome b-c1 complex subunit 2, mitochondrial (chains B, O)
AGVPPHPQDLEFTRLPNGLVIASLENYAPASRIGLFIKAGSRYENSNNLGTSHLLRLASS
LTTKGASSFKITRGIEAVGGKLSVTSTRENMAYTVECLRDDVDILMEFLLNVTTAPEFRR
WEVAALQPQLRIDKAVALQNPQAHVIENLHAAAYRNALANSLYCPDYRIGKVTPVELHDY
VQNHFTSARMALIGLGVSHPVLKQVAEQFLNIRGGLGLSGAKAKYHGGEIREQNGDSLVH
AALVAESAAIGSAEANAFSVLQHVLGAGPHVKRGSNATSSLYQAVAKGVHQPFDVSAFNA
SYSDSGLFGFYTISQAASAGDVIKAAYNQVKTIAQGNLSNPDVQAAKNKLKAGYLMSVES
SEGFLDEVGSQALAAGSYTPPSTVLQQIDAVADADVINAAKKFVSGRKSMAASGNLGHTP
FIDEL

Sequence of entity 3 (C, P), FASTA

>9W2X_3 Cytochrome b (chains C, P)
TNIRKSHPLMKIVNNAFIDLPAPSNISSWWNFGSLLGICLILQILTGLFLAMHYTSDTTT
AFSSVTHICRDVNYGWIIRYMHANGASMFFICLYMHVGRGLYYGSYTFLETWNIGVILLL
TVMATAFMGYVLPWGQMSFWGATVITNLLSAIPYIGTNLVEWIWGGFSVDKATLTRFFAF
HFILPFIIMAIAMVHLLFLHETGSNNPTGISSDVDKIPFHPYYTIKDILGALLLILALML
LVLFAPDLLGDPDNYTPANPLNTPPHIKPEWYFLFAYAILRSIPNKLGGVLALAFSILIL
ALIPLLHTSKQRSMMFRPLSQCLFWALVADLLTLTWIGGQPVEHPYITIGQLASVLYFLL
ILVLMPTAGTIENKLLKW

Sequence of entity 4 (D, Q), FASTA

>9W2X_4 Cytochrome c1, heme protein, mitochondrial (chains D, Q)
SDLELHPPSYPWSHRGLLSSLDHTSIRRGFQVYKQVCSSCHSMDYVAYRHLVGVCYTEDE
AKALAEEVEVQDGPNEDGEMFMRPGKLSDYFPKPYPNPEAARAANNGALPPDLSYIVRAR
HGGEDYVFSLLTGYCEPPTGVSLREGLYFNPYFPGQAIGMAPPIYNEVLEFDDGTPATMS
QVAKDVCTFLRWAAEPEHDHRKRMGLKMLLMMGLLLPLVYAMKRHKWSVLKSRKLAYRPP
K

Sequence of entity 5 (E, R), FASTA

>9W2X_5 Cytochrome b-c1 complex subunit Rieske, mitochondrial (chains E, R)
SHTDIKVPDFSDYRRPEVLDSTKSSKESSEARKGFSYLVTATTTVGVAYAAKNVVSQFVS
SMSASADVLAMSKIEIKLSDIPEGKNMAFKWRGKPLFVRHRTKKEIDQEAAVEVSQLRDP
QHDLERVKKPEWVILIGVCTHLGCVPIANAGDFGGYYCPCHGSHYDASGRIRKGPAPLNL
EVPSYEFTSDDMVIVG

Sequence of entity 6 (F, S), FASTA

>9W2X_6 Cytochrome b-c1 complex subunit 7 (chains F, S)
VSASSRWLEGIRKWYYNAAGFNKLGLMRDDTIHENDDVKEAIRRLPENLYDDRVFRIKRA
LDLSMRQQILPKEQWTKYEEDKSYLEPYLKEVIRERKEREEWAKK

Sequence of entity 7 (G, T), FASTA

>9W2X_7 Cytochrome b-c1 complex subunit 8 (chains G, T)
GRQFGHLTRVRHVITYSLSPFEQRAFPHYFSKGIPNVLRRTRACILRVAPPFVAFYLVYT
WGTQEFEKSKRKNPAAYEND

Sequence of entity 8 (H, U), FASTA

>9W2X_8 Cytochrome b-c1 complex subunit 6, mitochondrial (chains H, U)
ELVDPLTTVREQCEQLEKCVKARERLELCDERVSSRSQTEEDCTEELLDFLHARDHCVAH
KLFNSLK

Sequence of entity 9 (I, V), FASTA

>9W2X_9 Cytochrome b-c1 complex subunit 9 (chains I, V)
MLSVAARSGPFAPVLSATSRGVAGALRPLVQAAVPATSESPVLDLKRSVLCRESLRG

Sequence of entity 10 (J, W), FASTA

>9W2X_10 Cytochrome b-c1 complex subunit 9 (chains J, W)
VAPTLTARLYSLLFRRTSTFALTIVVGALFFERAFDQGADAIYEHINEGKLWKHIKHKYE
N

Sequence of entity 11 (K, X), FASTA

>9W2X_11 Cytochrome b-c1 complex subunit 10 (chains K, X)
LTRFLGPRYRQLARNWVPTAQLWGAVGAVGLVWATDSRLILDWVPYINGKFK

Ligands and cofactors

ID	Name	Formula	Copies
HEM	Protoporphyrin IX containing FE	C34 H32 Fe N4 O4	4
HEC	Heme C	C34 H36 Fe N4 O4	2
FES	FE2/S2 (inorganic) cluster	Fe2 S2	2

Primary citation

Structures of respiratory supercomplexes and ATP synthase oligomers in mammalian mitochondrial inner membrane. Nakano, A., Masuya, T., Akisada, S. et al. Nat Commun (2026) 17. DOI 10.1038/s41467-026-70578-x · PubMed

Other PDB entries of the same protein (UniProt P31800 (AlphaFold model), which also has an AlphaFold model), best resolution first:

1PP9 2.1 Å, Bovine cytochrome bc1 complex with stigmatellin bound
1PPJ 2.1 Å, Bovine cytochrome bc1 complex with stigmatellin and antimycin
2A06 2.1 Å, Bovine cytochrome bc1 complex with stigmatellin bound
2FYU 2.26 Å, Crystal structure of bovine heart mitochondrial bc1 with jg144 inhibitor
1L0L 2.35 Å, structure of bovine mitochondrial cytochrome bc1 complex with a bound fungicide famoxadone
1NTM 2.4 Å, Crystal Structure of Mitochondrial Cytochrome bc1 Complex at 2.4 Angstrom
9W2Y 2.4 Å, Cryo-EM structure of complex III on the bovine heart submitochondrial particles, III-2
1L0N 2.6 Å, native structure of bovine mitochondrial cytochrome bc1 complex
1NTK 2.6 Å, Crystal Structure of Mitochondrial Cytochrome bc1 in Complex with Antimycin A1
1NTZ 2.6 Å, Crystal Structure of Mitochondrial Cytochrome bc1 Complex Bound with Ubiquinone
1SQX 2.6 Å, Crystal Structure Analysis of Bovine Bc1 with Stigmatellin A
5KLV 2.65 Å, Structure of bos taurus cytochrome bc1 with fenamidone inhibited

Browse structure collections

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