9SMN: BRCA1-A complex

BRCA1-A complex bound to K63-polyUbATA - open form StateC StateP. Determined by electron microscopy at 3.2 Å resolution. Released 17 Jun 2026.

Method: Electron microscopy
Resolution: 3.2 Å
Organism: Homo sapiens
Chains: 18
Atoms: 24,768
Mol. weight: 437.61 kDa
Ligands: ZN
Released: 17 Jun 2026

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

Secondary structure: helices and β-sheets

9SMN contains 113 α-helices and 167 β-strands across 18 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: 10 helices, 14 β-strands

Element	Residues	Length	Sheet
β-strand	7-11	5	1
α-helix	12-24	13
β-strand	29-46	18	1
β-strand	50-67	18	1
β-strand	74	1	2
β-strand	80	1	2
α-helix	82-88	7
β-strand	95-102	8	1
α-helix	112-125	14
β-strand	131-139	9	1
β-strand	146-154	9	1
α-helix	156-158	3
β-strand	163-164	2	1
α-helix	165	1
β-strand	166-169	4	1
α-helix	171-173	3
α-helix	176-179	4
α-helix	189-202	14
β-strand	203	1	3
β-strand	209	1	3
α-helix	210-270	61
α-helix	278-287	10
β-strand	298-300	3	4
β-strand	306	1	4

Chain B: 9 helices, 13 β-strands

Element	Residues	Length	Sheet
β-strand	11-15	5	1
α-helix	16-26	11
β-strand	35-43	9	1
β-strand	71-79	9	1
β-strand	84-85	2	5
β-strand	90-91	2	5
α-helix	94-111	18
β-strand	116-122	7	1
β-strand	125	1	6
α-helix	131-132	2
α-helix	133-145	13
β-strand	150-155	6	1
β-strand	156	1	6
β-strand	159-160	2	1
β-strand	165-177	13	1
α-helix	207-208	2
β-strand	209-213	5	1
β-strand	216-219	4	1
α-helix	226-251	26
α-helix	258-275	18
α-helix	276-280	5
α-helix	281-314	34

Chain C: 16 helices, 16 β-strands

Element	Residues	Length	Sheet
α-helix	3-8	6
β-strand	10	1	7
α-helix	15-24	10
β-strand	37-41	5	8
β-strand	53	1	7
β-strand	55-62	8	8
β-strand	65-72	8	8
α-helix	81-82	2
β-strand	83-85	3	8
α-helix	100-103	4
α-helix	112-134	23
α-helix	136-147	12
α-helix	149-152	4
β-strand	155-159	5	9
α-helix	160-161	2
β-strand	171-176	6	9
α-helix	184-186	3
β-strand	194-195	2	10
β-strand	201-207	7	9
β-strand	215-221	7	9
α-helix	222	1
α-helix	223-229	7
α-helix	237-240	4
α-helix	246-248	3
α-helix	250-281	32
α-helix	283-285	3
β-strand	286-289	4	11
β-strand	296-303	8	11
β-strand	306-313	8	11
β-strand	324-333	10	11
β-strand	339-343	5	11
α-helix	355-379	25

Chain D: 8 helices, 11 β-strands

Element	Residues	Length	Sheet
β-strand	82-84	3	4
β-strand	93-99	7	12
β-strand	111	1	13
α-helix	120-139	20
β-strand	143-150	8	12
β-strand	152-160	9	12
α-helix	163-171	9
α-helix	183-193	11
α-helix	206-207	2
β-strand	210-216	7	12
α-helix	230-236	7
β-strand	241-242	2	12
β-strand	245-246	2	12
β-strand	247	1	14
α-helix	255-271	17
β-strand	281	1	14
β-strand	287	1	13
α-helix	288-297	10
α-helix	302-304	3

Chain E: 3 helices, 3 β-strands

Element	Residues	Length	Sheet
β-strand	273-276	4	4
α-helix	289-313	25
β-strand	316-317	2	10
α-helix	323	1
β-strand	324	1	9
α-helix	326-328	3

Chain F: 11 helices, 12 β-strands

Element	Residues	Length	Sheet
β-strand	5-11	7	15
α-helix	12-24	13
β-strand	29-41	13	15
β-strand	55-67	13	15
β-strand	74	1	16
α-helix	79	1
β-strand	80	1	16
α-helix	81	1
α-helix	82-88	7
β-strand	95-102	8	15
α-helix	112-125	14
β-strand	131-139	9	15
β-strand	146-154	9	15
β-strand	166-169	4	15
α-helix	171-173	3
α-helix	175-177	3
α-helix	189-202	14
β-strand	203	1	17
β-strand	209	1	17
α-helix	210-268	59
α-helix	278-286	9
α-helix	292-294	3
β-strand	298-300	3	18

Chain G: 9 helices, 10 β-strands

Element	Residues	Length	Sheet
β-strand	11-15	5	15
α-helix	16-26	11
β-strand	35-42	8	15
β-strand	71-79	9	15
β-strand	84-85	2	19
β-strand	90-91	2	19
α-helix	99-111	13
β-strand	116-123	8	15
α-helix	131-132	2
α-helix	133-145	13
β-strand	150-160	11	15
β-strand	165-177	13	15
β-strand	209-213	5	15
β-strand	216-219	4	15
α-helix	220	1
α-helix	226-251	26
α-helix	258-275	18
α-helix	276-280	5
α-helix	281-315	35

Chain H: 15 helices, 15 β-strands

Element	Residues	Length	Sheet
α-helix	3-8	6
α-helix	12-14	3
α-helix	15-24	10
β-strand	37-42	6	20
β-strand	53-62	10	20
β-strand	65-72	8	20
α-helix	81-82	2
β-strand	83-85	3	20
α-helix	87-89	3
α-helix	100-103	4
α-helix	112-134	23
α-helix	136-147	12
α-helix	149-153	5
β-strand	155-158	4	21
β-strand	171-176	6	21
α-helix	184-186	3
β-strand	201-207	7	21
β-strand	216-221	6	21
α-helix	223-228	6
β-strand	237	1	22
α-helix	238-241	4
α-helix	246-282	37
α-helix	283-285	3
β-strand	286-289	4	23
β-strand	296-302	7	23
β-strand	307-313	7	23
β-strand	324-333	10	23
β-strand	339-344	6	23
α-helix	355-377	23
β-strand	382	1	23

10 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
BRCA1-A complex subunit Abraxas 1	A, F	protein	409	Homo sapiens	Q6UWZ7 (AlphaFold model)
Lys-63-specific deubiquitinase BRCC36	B, G	protein	316	Homo sapiens	P46736 (AlphaFold model)
BRISC and BRCA1-A complex member 2	C, H	protein	383	Homo sapiens	Q9NXR7 (AlphaFold model)
BRISC and BRCA1-A complex member 1	D, I	protein	349	Homo sapiens	Q9NWV8 (AlphaFold model)
BRCA1-A complex subunit RAP80	E, J	protein	171	Homo sapiens	Q96RL1
Polyubiquitin-C	K, M	protein	76	Homo sapiens	P0CG48
Polyubiquitin-C	L, N	protein	76	Homo sapiens	P0CG48
Ubiquitin	S, T, U, V	protein	76	Homo sapiens	P0CG48

Sequence of entity 1 (A, F), FASTA

>9SMN_1 BRCA1-A complex subunit Abraxas 1 (chains A, F)
MEGESTSAVLSGFVLGALAFQHLNTDSDTEGFLLGEVKGEAKNSITDSQMDDVEVVYTID
IQKYIPCYQLFSFYNSSGEVNEQALKKILSNVKKNVVGWYKFRRHSDQIMTFRERLLHKN
LQEHFSNQDLVFLLLTPSIITESCSTHRLEHSLYKPQKGLFHRVPLVVANLGMSEQLGYK
TVSGSCMSTGFSRAVQTHSSKFFEEDGSLKEVHKINEMYASLQEELKSICKKVEDSEQAV
DKLVKDVNRLKREIEKRRGAQIQAAREKNIQKDPQENIFLCQALRTFFPNSEFLHSCVMS
LKNRHVSKSSCNYNHHLDVVDNLTLMVEHTDIPEASPASTPQIIKHKALDLDDRWQFKRS
RLLDTQDKRSKADTGSSNQDKASKMSSPETDEEIEKMKGFGEYSRSPTF

Sequence of entity 2 (B, G), FASTA

>9SMN_2 Lys-63-specific deubiquitinase BRCC36 (chains B, G)
MAVQVVQAVQAVHLESDAFLVCLNHALSTEKEEVMGLCIGELNDDTRSDSKFAYTGTEMR
TVAEKVDAVRIVHIHSVIILRRSDKRKDRVEISPEQLSAASTEAERLAELTGRPMRVVGW
YHSHPHITVWPSHVDVRTQAMYQMMDQGFVGLIFSCFIEDKNTKTGRVLYTCFQSIQAQK
SSESLHGPRDFWSSSQHISIEGQKEEERYERIEIPIHIVPHVTIGKVCLESAVELPKILC
QEEQDAYRRIHSLTHLDSVTKIHNGSVFTKNLCSQMSAVSGPLLQWLEDRLEQNQQHLQE
LQQEKEELMQELSSLE

Sequence of entity 3 (C, H), FASTA

>9SMN_3 BRISC and BRCA1-A complex member 2 (chains C, H)
MSPEVALNRISPMLSPFISSVVRNGKVGLDATNCLRITDLKSGCTSLTPGPNCDRFKLHI
PYAGETLKWDIIFNAQYPELPPDFIFGEDAEFLPDPSALQNLASWNPSNPECLLLVVKEL
VQQYHQFQCSRLRESSRLMFEYQTLLEEPQYGENMEIYAGKKNNWTGEFSARFLLKLPVD
FSNIPTYLLKDVNEDPGEDVALLSVSFEDTEATQVYPKLYLSPRIEHALGGSSALHIPAF
PGGGCLIDYVPQVCHLLTNKVQYVIQGYHKRREYIAAFLSHFGTGVVEYDAEGFTKLTLL
LMWKDFCFLVHIDLPLFFPRDQPTLTFQSVYHFTNSGQLYSQAQKNYPYSPRWDGNEMAK
RAKAYFKTFVPQFQEAAFANGKL

Sequence of entity 4 (D, I), FASTA

>9SMN_4 BRISC and BRCA1-A complex member 1 (chains D, I)
MAHHHHHHSAALEVLFQGPGMEVAEPSSPTEEEEEEEEHSAEPRPRTRSNPEGAEDRAVG
AQASVGSRSEGEGEAASADDGSLNTSGAGPKSWQVPPPAPEVQIRTPRVNCPEKVIICLD
LSEEMSLPKLESFNGSKTNALNVSQKMIEMFVRTKHKIDKSHEFALVVVNDDTAWLSGLT
SDPRELCSCLYDLETASCSTFNLEGLFSLIQQKTELPVTENVQTIPPPYVVRTILVYSRP
PCQPQFSLTEPMKKMFQCPYFFFDVVYIHNGTEEKEEEMSWKDMFAFMGSLDTKGTSYKY
EVALAGPALELHNCMAKLLAHPLQRPCQSHASYSLLEEEDEAIEVEATV

Sequence of entity 5 (E, J), FASTA

>9SMN_5 BRCA1-A complex subunit RAP80 (chains E, J)
MASWSHPQFEKGALEVLFQGPGKGLQDTGGTVNYFWGIPFCPDGVDPNQYTKVILCQLEV
YQKSLKMAQRQLLNKKGFGEPVLPRPPSLIQNECGQGEQASEKNECISEDMGDEDKEERQ
ESRASDWHSKTKDFQESSIKSLKEKLLLEEEPTTSHGQSSQGIVEETSEEG

Sequence of entity 6 (K, M), FASTA

>9SMN_6 Polyubiquitin-C (chains K, M)
MQIFVKTLTGKTITLEVEPSDTIENVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLSDYN
IQAESTLHLVLRLRGG

Sequence of entity 7 (L, N), FASTA

>9SMN_7 Polyubiquitin-C (chains L, N)
MQIFVKTLTGKTITLEVEPSDTIENVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLSDYN
IQKESTLHLVLRLRGX

Sequence of entity 8 (S, T, U, V), FASTA

>9SMN_8 Ubiquitin (chains S, T, U, V)
MQIFVKTLTGKTITLEVEPSDTIENVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLSDYN
IQKESTLHLVLRLRGG

Ligands and cofactors

ID	Name	Formula	Copies
ZN	Zinc ion	Zn	2

Primary citation

A ubiquitin chain-feeding mechanism for BRCA1-A. Murachelli, A.G., El Oualid, F., Sixma, T.K. Nat Commun (2026) 17. DOI 10.1038/s41467-026-75797-w · PubMed

Other PDB entries of the same protein (UniProt Q6UWZ7 (AlphaFold model), which also has an AlphaFold model), best resolution first:

4Y2G 2.5 Å, Structure of BRCA1 BRCT domains in complex with Abraxas single phosphorylated peptide
9SQY 2.92 Å, Cryo-EM structure of the ARISC(E33A)-RAP80:K63-Ub7 complex (Composite map)
9SMP 3.0 Å, BRCA1-A complex bound to K63-polyUbATA - open form double State P
9SNA 3.2 Å, BRCA1-A complex bound to K63-diUbATA - open form StateC StateP
9SQW 3.2 Å, Cryo-EM structure of the ARISCdC(E33A):K63-Ub7 complex (Composite map)
9SQV 3.21 Å, Cryo-EM structure of the ARISCdC(E33A):K63-Ub4 complex (Composite map)
9SMR 3.25 Å, Structure of apo BRCA1-A complex in presence of K63-oligoUbATA
9SMS 3.3 Å, BRCA1-A complex: Ubiquitin bound to BRE at the wrist site (focused 3D class)
9SO9 3.4 Å, BRCA1-A complex bound to K63-oligoUbATA - closed form StateC*
4JLU 3.5 Å, Crystal structure of BRCA1 BRCT with doubly phosphorylated Abraxas
4Y18 3.5 Å, Structure of BRCA1 BRCT domains in complex with Abraxas double phosphorylated peptide
4U4A 3.51 Å, Complex Structure of BRCA1 BRCT with singly phospho Abraxas

Browse structure collections

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