9ULO: Human Mre11-Nbs1 complex

Cryo-EM structure of Human Mre11-Nbs1 complex. Determined by electron microscopy at 3.91 Å resolution. Released 22 Apr 2026.

Method: Electron microscopy
Resolution: 3.91 Å
Organism: Homo sapiens
Chains: 3
Atoms: 6,878
Mol. weight: 246.71 kDa
Ligands: MN
Released: 22 Apr 2026

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

Secondary structure: helices and β-sheets

9ULO contains 33 α-helices and 59 β-strands across 3 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: 15 helices, 27 β-strands

Element	Residues	Length	Sheet
α-helix	3-7	5
β-strand	13-18	6	1
β-strand	19	1	2
β-strand	23	1	3
α-helix	35-49	15
β-strand	54-57	4	1
β-strand	62	1	3
α-helix	69-82	14
β-strand	84	1	4
β-strand	92-93	2	5
α-helix	97-100	4
β-strand	116	1	6
β-strand	118	1	4
β-strand	122-124	3	1
β-strand	133	1	7
β-strand	138	1	7
α-helix	140-147	8
β-strand	150-152	3	1
β-strand	162-164	3	8
β-strand	167-171	5	5
β-strand	174-181	8	5
α-helix	186-194	9
β-strand	198-200	3	8
α-helix	207-209	3
β-strand	211-216	6	5
β-strand	240-243	4	5
β-strand	250-255	6	5
β-strand	262-265	4	5
β-strand	268	1	2
α-helix	276-279	4
α-helix	281-282	2
β-strand	283-290	8	1
β-strand	293-300	8	1
α-helix	305-306	2
β-strand	307-313	7	9
α-helix	314-316	3
α-helix	328-352	25
β-strand	362-368	7	9
α-helix	378-382	5
α-helix	383-385	3
α-helix	392-394	3
β-strand	396-399	4	9

Chain B: 17 helices, 30 β-strands

Element	Residues	Length	Sheet
α-helix	4-7	4
β-strand	13-18	6	10
β-strand	19	1	11
β-strand	23	1	12
α-helix	35-49	15
β-strand	54-57	4	10
β-strand	62	1	12
α-helix	69-83	15
β-strand	84	1	13
α-helix	87-89	3
β-strand	92-93	2	14
β-strand	95	1	15
α-helix	97-101	5
α-helix	110-112	3
β-strand	116	1	6
β-strand	118	1	13
β-strand	122-124	3	10
β-strand	133	1	16
β-strand	138	1	16
α-helix	140-147	8
β-strand	150-152	3	10
β-strand	162-164	3	17
β-strand	167-171	5	14
β-strand	174-180	7	14
α-helix	186-194	9
β-strand	198-200	3	17
β-strand	202-203	2	18
α-helix	207-209	3
β-strand	211-216	6	14
β-strand	240-243	4	14
β-strand	250-255	6	14
β-strand	262-265	4	14
β-strand	268	1	11
α-helix	276-279	4
α-helix	281-282	2
β-strand	283-290	8	10
β-strand	293-295	3	10
β-strand	298-300	3	10
α-helix	305-306	2
β-strand	307-313	7	19
α-helix	314-316	3
α-helix	328-351	24
β-strand	362-368	7	19
α-helix	378-382	5
α-helix	383-385	3
α-helix	392-394	3
β-strand	396-399	4	19

Chain C: 1 helix, 2 β-strands

Element	Residues	Length	Sheet
α-helix	690-692	3
β-strand	703	1	15
β-strand	708-709	2	18

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Double-strand break repair protein MRE11	A, B	protein	708	Homo sapiens	P49959 (AlphaFold model)
Nibrin	C	protein	754	Homo sapiens	O60934 (AlphaFold model)

Sequence of entity 1 (A, B), FASTA

>9ULO_1 Double-strand break repair protein MRE11 (chains A, B)
MSTADALDDENTFKILVATDIHLGFMEKDAVRGNDTFVTLDEILRLAQENEVDFILLGGD
LFHENKPSRKTLHTCLELLRKYCMGDRPVQFEILSDQSVNFGFSKFPWVNYQDGNLNISI
PVFSIHGNHDDPTGADALCALDILSCAGFVNHFGRSMSVEKIDISPVLLQKGSTKIALYG
LGSIPDERLYRMFVNKKVTMLRPKEDENSWFNLFVIHQNRSKHGSTNFIPEQFLDDFIDL
VIWGHEHECKIAPTKNEQQLFYISQPGSSVVTSLSPGEAVKKHVGLLRIKGRKMNMHKIP
LHTVRQFFMEDIVLANHPDIFNPDNPKVTQAIQSFCLEKIEEMLENAERERLGNSHQPEK
PLVRLRVDYSGGFEPFSVLRFSQKFVDRVANPKDIIHFFRHREQKEKTGEEINFGKLITK
PSEGTTLRVEDLVKQYFQTAEKNVQLSLLTERGMGEAVQEFVDKEEKDAIEELVKYQLEK
TQRFLKERHIDALEDKIDEEVRRFRETRQKNTNEEDDEVREAMTRARALRSQSEESASAF
SADDLMSIDLAEQMANDSDDSISAATNKGRGRGRGRRGGRGQNSASRGGSQRGRADTGLE
TSTRSRNSKTAVSASRNMSIIDAFKSTRQQPSRNVTTKNYSEVIEVDESDVEEDIFPTTS
KTDQRWSSTSSSKIMSQSQVSKGVDFESSEDDDDDPFMNTSSLRRNRR

Sequence of entity 2 (C), FASTA

>9ULO_2 Nibrin (chains C)
MWKLLPAAGPAGGEPYRLLTGVEYVVGRKNCAILIENDQSISRNHAVLTANFSVTNLSQT
DEIPVLTLKDNSKYGTFVNEEKMQNGFSRTLKSGDGITFGVFGSKFRIEYEPLVACSSCL
DVSGKTALNQAILQLGGFTVNNWTEECTHLVMVSVKVTIKTICALICGRPIVKPEYFTEF
LKAVESKKQPPQIESFYPPLDEPSIGSKNVDLSGRQERKQIFKGKTFIFLNAKQHKKLSS
AVVFGGGEARLITEENEEEHNFFLAPGTCVVDTGITNSQTLIPDCQKKWIQSIMDMLQRQ
GLRPIPEAEIGLAVIFMTTKNYCDPQGHPSTGLKTTTPGPSLSQGVSVDEKLMPSAPVNT
TTYVADTESEQADTWDLSERPKEIKVSKMEQKFRMLSQDAPTVKESCKTSSNNNSMVSNT
LAKMRIPNYQLSPTKLPSINKSKDRASQQQQTNSIRNYFQPSTKKRERDEENQEMSSCKS
ARIETSCSLLEQTQPATPSLWKNKEQHLSENEPVDTNSDNNLFTDTDLKSIVKNSASKSH
AAEKLRSNKKREMDDVAIEDEVLEQLFKDTKPELEIDVKVQKQEEDVNVRKRPRMDIETN
DTFSDEAVPESSKISQENEIGKKRELKEDSLWSAKEISNNDKLQDDSEMLPKKLLLTEFR
SLVIKNSTSRNPSGINDDYGQLKNFKKFKKVTYPGAGKLPHIIGGSDLIAHHARKNTELE
EWLRQEMEVQNQHAKEESLADDLFRYNPYLKRRR

Ligands and cofactors

ID	Name	Formula	Copies
MN	Manganese (II) ion	Mn	4

Primary citation

Structural Insights into ATM-dependent Phophorylation of MRN Complex. Sun, Y., Ying, S. To be published.

Other PDB entries of the same protein (UniProt P49959 (AlphaFold model), which also has an AlphaFold model), best resolution first:

8K00 1.4 Å, RPA70N-MRE11 fusion
9Q9K 2.59 Å, Cryo-EM structure of human Mre11-Rad50 (MR) complex bound to DNA and telomeric factor…
9Q9J 2.71 Å, Cryo-EM structure of human Mre11-Rad50-Nbs1 (MRN) complex bound to DNA and telomeric…
9Q9I 2.79 Å, Cryo-EM structure of human Mre11-Rad50-Nbs1 complex bound to DNA
9Q9M 2.81 Å, Cryo-EM structure of human Mre11-Rad50-Nbs1 (MRN) complex bound to DNA and telomeric…
3T1I 3.0 Å, Crystal Structure of Human Mre11: Understanding Tumorigenic Mutations
9Q9H 3.11 Å, Cryo-EM structure of human Mre11-Rad50 complex bound to DNA
8BAH 4.13 Å, Human Mre11-Nbs1 complex

Browse structure collections

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