9SMR: BRCA1-A complex subunit Abraxas 1

Structure of apo BRCA1-A complex in presence of K63-oligoUbATA. Determined by electron microscopy at 3.25 Å resolution. Released 8 Jul 2026.

Method: Electron microscopy
Resolution: 3.25 Å
Organism: Homo sapiens
Chains: 10
Atoms: 19,528
Mol. weight: 368.93 kDa
Ligands: ZN
Released: 8 Jul 2026

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

Secondary structure: helices and β-sheets

9SMR contains 86 α-helices and 106 β-strands across 10 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: 8 helices, 14 β-strands

Element	Residues	Length	Sheet
β-strand	8-11	4	1
α-helix	12-23	12
β-strand	29-41	13	1
β-strand	55-66	12	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	166-169	4	1
α-helix	171-173	3
α-helix	189-202	14
β-strand	203	1	3
β-strand	209	1	3
α-helix	210-268	59
α-helix	278-287	10
β-strand	299-300	2	4
β-strand	305	1	5
β-strand	306	1	4

Chain B: 8 helices, 9 β-strands

Element	Residues	Length	Sheet
β-strand	11-15	5	1
α-helix	16-26	11
β-strand	35-41	7	1
β-strand	71-80	10	1
α-helix	94-111	18
β-strand	116-125	10	1
α-helix	131-132	2
α-helix	133-145	13
β-strand	150-159	10	1
β-strand	166-173	8	1
β-strand	174-177	4	6
β-strand	209-212	4	6
β-strand	216-219	4	1
α-helix	226-251	26
α-helix	258-275	18
α-helix	276-280	5
α-helix	281-313	33

Chain C: 15 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	36-42	7	7
α-helix	49	1
α-helix	51	1
β-strand	53-61	9	7
β-strand	66-72	7	7
α-helix	81-82	2
β-strand	83-85	3	7
α-helix	100-103	4
α-helix	113-133	21
α-helix	136-147	12
α-helix	149-152	4
β-strand	155-158	4	8
β-strand	171-176	6	8
α-helix	184-186	3
β-strand	194-195	2	9
β-strand	201-207	7	8
β-strand	215-221	7	8
α-helix	223-229	7
β-strand	237	1	10
α-helix	238-241	4
α-helix	250-281	32
β-strand	286-289	4	11
β-strand	296-303	8	11
β-strand	306-313	8	11
α-helix	322-323	2
β-strand	324-334	11	11
β-strand	338-343	6	11
α-helix	358-380	23

Chain D: 8 helices, 11 β-strands

Element	Residues	Length	Sheet
β-strand	82-84	3	4
β-strand	93	1	12
β-strand	94-99	6	13
β-strand	110	1	14
β-strand	118	1	14
α-helix	120-138	19
β-strand	143-149	7	13
β-strand	153-160	8	13
α-helix	163-171	9
α-helix	184-193	10
α-helix	195-197	3
α-helix	206-207	2
β-strand	210	1	12
β-strand	211-217	7	13
α-helix	230-237	8
β-strand	241-249	9	13
α-helix	261-270	10
β-strand	279-283	5	13
α-helix	288-298	11

Chain E: 3 helices, 4 β-strands

Element	Residues	Length	Sheet
β-strand	273-276	4	4
α-helix	283-284	2
β-strand	285	1	5
α-helix	289-312	24
β-strand	316-317	2	9
β-strand	326	1	10
α-helix	327-328	2

Chain F: 7 helices, 12 β-strands

Element	Residues	Length	Sheet
β-strand	5-11	7	15
α-helix	12-23	12
β-strand	29-42	14	15
β-strand	45	1	16
β-strand	51	1	16
β-strand	54-67	14	15
α-helix	84-88	5
β-strand	96-102	7	15
α-helix	112-116	5
α-helix	119-124	6
β-strand	132-138	7	15
β-strand	147-154	8	15
β-strand	163	1	15
β-strand	166-169	4	15
α-helix	177-179	3
α-helix	189-197	9
β-strand	203	1	17
β-strand	209	1	17
α-helix	212-258	47

Chain G: 10 helices, 8 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	71-80	10	15
α-helix	95-97	3
α-helix	99-111	13
β-strand	116-125	10	15
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	226-229	4
α-helix	234-251	18
α-helix	258-275	18
α-helix	276-280	5
α-helix	281-315	35

Chain H: 14 helices, 22 β-strands

Element	Residues	Length	Sheet
α-helix	3-9	7
β-strand	10	1	18
α-helix	15-24	10
β-strand	36-41	6	19
β-strand	53	1	18
β-strand	55-62	8	19
β-strand	65-72	8	19
α-helix	81-82	2
β-strand	83-85	3	19
α-helix	100-103	4
α-helix	112-132	21
α-helix	136-147	12
α-helix	149-153	5
β-strand	155-156	2	20
α-helix	161-163	3
β-strand	171-176	6	20
α-helix	185-186	2
β-strand	201-207	7	20
β-strand	215	1	20
β-strand	218-221	4	20
α-helix	223-228	6
β-strand	237	1	21
α-helix	238-241	4
α-helix	249-282	34
β-strand	286-289	4	22
β-strand	296-299	4	22
β-strand	302	1	23
β-strand	303	1	24
β-strand	306	1	24
β-strand	309-313	5	22
β-strand	324-328	5	22
β-strand	333	1	25
α-helix	339-340	2
β-strand	342-343	2	22
α-helix	355-377	23
β-strand	382	1	25

2 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

Sequence of entity 1 (A, F), FASTA

>9SMR_1 BRCA1-A complex subunit Abraxas 1 (chains A, F)
MEGESTSAVLSGFVLGALAFQHLNTDSDTEGFLLGEVKGEAKNSITDSQMDDVEVVYTID
IQKYIPCYQLFSFYNSSGEVNEQALKKILSNVKKNVVGWYKFRRHSDQIMTFRERLLHKN
LQEHFSNQDLVFLLLTPSIITESCSTHRLEHSLYKPQKGLFHRVPLVVANLGMSEQLGYK
TVSGSCMSTGFSRAVQTHSSKFFEEDGSLKEVHKINEMYASLQEELKSICKKVEDSEQAV
DKLVKDVNRLKREIEKRRGAQIQAAREKNIQKDPQENIFLCQALRTFFPNSEFLHSCVMS
LKNRHVSKSSCNYNHHLDVVDNLTLMVEHTDIPEASPASTPQIIKHKALDLDDRWQFKRS
RLLDTQDKRSKADTGSSNQDKASKMSSPETDEEIEKMKGFGEYSRSPTF

Sequence of entity 2 (B, G), FASTA

>9SMR_2 Lys-63-specific deubiquitinase BRCC36 (chains B, G)
MAVQVVQAVQAVHLESDAFLVCLNHALSTEKEEVMGLCIGELNDDTRSDSKFAYTGTEMR
TVAEKVDAVRIVHIHSVIILRRSDKRKDRVEISPEQLSAASTEAERLAELTGRPMRVVGW
YHSHPHITVWPSHVDVRTQAMYQMMDQGFVGLIFSCFIEDKNTKTGRVLYTCFQSIQAQK
SSESLHGPRDFWSSSQHISIEGQKEEERYERIEIPIHIVPHVTIGKVCLESAVELPKILC
QEEQDAYRRIHSLTHLDSVTKIHNGSVFTKNLCSQMSAVSGPLLQWLEDRLEQNQQHLQE
LQQEKEELMQELSSLE

Sequence of entity 3 (C, H), FASTA

>9SMR_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

>9SMR_4 BRISC and BRCA1-A complex member 1 (chains D, I)
MAHHHHHHSAALEVLFQGPGMEVAEPSSPTEEEEEEEEHSAEPRPRTRSNPEGAEDRAVG
AQASVGSRSEGEGEAASADDGSLNTSGAGPKSWQVPPPAPEVQIRTPRVNCPEKVIICLD
LSEEMSLPKLESFNGSKTNALNVSQKMIEMFVRTKHKIDKSHEFALVVVNDDTAWLSGLT
SDPRELCSCLYDLETASCSTFNLEGLFSLIQQKTELPVTENVQTIPPPYVVRTILVYSRP
PCQPQFSLTEPMKKMFQCPYFFFDVVYIHNGTEEKEEEMSWKDMFAFMGSLDTKGTSYKY
EVALAGPALELHNCMAKLLAHPLQRPCQSHASYSLLEEEDEAIEVEATV

Sequence of entity 5 (E, J), FASTA

>9SMR_5 BRCA1-A complex subunit RAP80 (chains E, J)
MASWSHPQFEKGALEVLFQGPGKGLQDTGGTVNYFWGIPFCPDGVDPNQYTKVILCQLEV
YQKSLKMAQRQLLNKKGFGEPVLPRPPSLIQNECGQGEQASEKNECISEDMGDEDKEERQ
ESRASDWHSKTKDFQESSIKSLKEKLLLEEEPTTSHGQSSQGIVEETSEEG

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
9SMN 3.2 Å, BRCA1-A complex bound to K63-polyUbATA - open form StateC StateP
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)
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

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