9MCB: Human UBA1-UBE2O-Ub -Recruitment state 1

Cryo-EM structure of Human UBA1-UBE2O-Ub -Recruitment state 1. Determined by electron microscopy at 3.42 Å resolution. Released 25 Mar 2026.

Method: Electron microscopy
Resolution: 3.42 Å
Organism: Homo sapiens
Chains: 3
Atoms: 10,729
Mol. weight: 157.77 kDa
Ligands: AMP
Released: 25 Mar 2026

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

Secondary structure: helices and β-sheets

9MCB contains 82 α-helices and 66 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: 65 helices, 50 β-strands

Element	Residues	Length	Sheet
α-helix	56-70	15
β-strand	74-78	5	1
α-helix	83-94	12
β-strand	98-102	5	1
α-helix	105	1
β-strand	106	1	2
α-helix	107	1
α-helix	109-113	5
α-helix	120-122	3
β-strand	126	1	2
α-helix	127-135	9
β-strand	144-147	4	1
α-helix	156-158	3
β-strand	161-165	5	1
α-helix	169-181	13
β-strand	185-192	8	1
β-strand	195-201	7	1
β-strand	206-208	3	3
α-helix	215-217	3
β-strand	218-220	3	4
β-strand	221-225	5	5
β-strand	230-234	5	5
β-strand	247-251	5	4
β-strand	254	1	6
α-helix	262-264	3
β-strand	265-266	2	4
β-strand	269	1	5
β-strand	274-277	4	5
α-helix	284-286	3
β-strand	288	1	6
β-strand	291-294	4	4
β-strand	299-301	3	3
α-helix	306-311	6
β-strand	316	1	1
α-helix	320-322	3
α-helix	325-343	19
α-helix	346-348	3
α-helix	352-368	17
α-helix	380-388	9
α-helix	395-414	20
α-helix	418-420	3
β-strand	424-427	4	1
α-helix	429-431	3
α-helix	441-444	4
α-helix	452-458	7
α-helix	461-468	8
β-strand	471-474	4	7
α-helix	478-490	13
β-strand	500-503	4	7
β-strand	507	1	8
α-helix	508	1
α-helix	510-514	5
α-helix	521-523	3
β-strand	527	1	8
α-helix	528-539	12
β-strand	545-548	4	7
α-helix	550-552	3
α-helix	562-567	6
β-strand	570-573	4	7
α-helix	578-591	14
β-strand	595-601	7	7
β-strand	604-610	7	7
β-strand	615	1	9
α-helix	618-620	3
α-helix	624-626	3
α-helix	631-635	5
α-helix	641-652	12
α-helix	653-657	5
α-helix	658-668	11
α-helix	672-677	6
α-helix	683-692	10
α-helix	693-697	5
α-helix	703-714	12
α-helix	715-719	5
α-helix	720-728	9
β-strand	734	1	10
β-strand	740	1	10
α-helix	759-763	5
α-helix	764-776	13
α-helix	784-791	8
α-helix	811-816	6
α-helix	819-821	3
α-helix	823-832	10
α-helix	834-835	2
α-helix	836-838	3
α-helix	858-872	15
α-helix	875-877	3
α-helix	880-887	8
α-helix	890-892	3
α-helix	895-914	20
α-helix	919-921	3
β-strand	924-928	5	7
β-strand	933-937	5	7
β-strand	938	1	11
α-helix	939-940	2
β-strand	941	1	9
α-helix	942-943	2
β-strand	945-947	3	12
β-strand	950-952	3	12
β-strand	958-961	4	13
β-strand	963	1	14
β-strand	969	1	14
α-helix	970	1
β-strand	971	1	15
α-helix	972-981	10
β-strand	986-992	7	16
β-strand	995-998	4	16
α-helix	1004-1010	7
β-strand	1014	1	15
α-helix	1015-1023	9
α-helix	1026-1028	3
β-strand	1033-1036	4	13
β-strand	1037-1041	5	16
β-strand	1047-1049	3	16
β-strand	1053-1056	4	13

Chain B: 14 helices, 8 β-strands

Element	Residues	Length	Sheet
β-strand	930-932	3	17
α-helix	940-943	4
α-helix	951-968	18
β-strand	973-978	6	17
β-strand	984-990	7	17
α-helix	991-992	2
β-strand	1001-1007	7	17
α-helix	1012-1014	3
α-helix	1016-1017	2
β-strand	1018-1020	3	17
β-strand	1033	1	18
β-strand	1038	1	17
β-strand	1039	1	18
α-helix	1061-1067	7
α-helix	1068-1072	5
α-helix	1085-1087	3
α-helix	1091-1117	27
α-helix	1124-1130	7
α-helix	1133-1139	7
α-helix	1144-1151	8
α-helix	1250-1252	3
α-helix	1263-1282	20

Chain C: 3 helices, 8 β-strands

Element	Residues	Length	Sheet
β-strand	2-7	6	11
β-strand	12-16	5	11
β-strand	22	1	19
α-helix	23-33	11
α-helix	38-40	3
β-strand	42-45	4	11
β-strand	48-49	2	11
β-strand	55	1	19
α-helix	56-59	4
β-strand	66-70	5	11
β-strand	75	1	7

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Ubiquitin-like modifier-activating enzyme 1	A	protein	1058	Homo sapiens	P22314 (AlphaFold model)
(E3-independent) E2 ubiquitin-conjugating enzyme	B	protein	271	Homo sapiens	Q9C0C9 (AlphaFold model)
Ubiquitin	C	protein	76	Homo sapiens	P0CG47 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>9MCB_1 Ubiquitin-like modifier-activating enzyme 1 (chains A)
MSSSPLSKKRRVSGPDPKPGSNCSPAQSVLSEVPSVPTNGMAKNGSEADIDEGLYSRQLY
VLGHEAMKRLQTSSVLVSGLRGLGVEIAKNIILGGVKAVTLHDQGTAQWADLSSQFYLRE
EDIGKNRAEVSQPRLAELNSYVPVTAYTGPLVEDFLSGFQVVVLTNTPLEDQLRVGEFCH
NRGIKLVVADTRGLFGQLFCDFGEEMILTDSNGEQPLSAMVSMVTKDNPGVVTCLDEARH
GFESGDFVSFSEVQGMVELNGNQPMEIKVLGPYTFSICDTSNFSDYIRGGIVSQVKVPKK
ISFKSLVASLAEPDFVVTDFAKFSRPAQLHIGFQALHQFCAQHGRPPRPRNEEDAAELVA
LAQAVNARALPAVQQNNLDEDLIRKLAYVAAGDLAPINAFIGGLAAQEVMKACSGKFMPI
MQWLYFDALECLPEDKEVLTEDKCLQRQNRYDGQVAVFGSDLQEKLGKQKYFLVGAGAIG
CELLKNFAMIGLGCGEGGEIIVTDMDTIEKSNLNRQFLFRPWDVTKLKSDTAAAAVRQMN
PHIRVTSHQNRVGPDTERIYDDDFFQNLDGVANALDNVDARMYMDRRCVYYRKPLLESGT
LGTKGNVQVVIPFLTESYSSSQDPPEKSIPICTLKNFPNAIEHTLQWARDEFEGLFKQPA
ENVNQYLTDPKFVERTLRLAGTQPLEVLEAVQRSLVLQRPQTWADCVTWACHHWHTQYSN
NIRQLLHNFPPDQLTSSGAPFWSGPKRCPHPLTFDVNNPLHLDYVMAAANLFAQTYGLTG
SQDRAAVATFLQSVQVPEFTPKSGVKIHVSDQELQSANASVDDSRLEELKATLPSPDKLP
GFKMYPIDFEKDDDSNFHMDFIVAASNLRAENYDIPSADRHKSKLIAGKIIPAIATTTAA
VVGLVCLELYKVVQGHRQLDSYKNGFLNLALPFFGFSEPLAAPRHQYYNQEWTLWDRFEV
QGLQPNGEEMTLKQFLDYFKTEHKLEITMLSQGVSMLYSFFMPAAKLKERLDQPMTEIVS
RVSKRKLGRHVRALVLELCCNDESGEDVEVPYVRYTIR

Sequence of entity 2 (B), FASTA

>9MCB_2 (E3-independent) E2 ubiquitin-conjugating enzyme (chains B)
VFSVLEFAPSNHSFKKIEFQPPEAKKFFSTVRKEMALLATSLPEGIMVKTFEDRMDLFSA
LIKGPTRTPYEDGLYLFDIQLPNIYPAVPPHFCYLSQCSGRLNPNLYDNGKVCVSLLGTW
IGKGTERWTSKSSLLQVLISIQGLILVNEPYYNEAGFDSDRGLQEGYENSRCYNEMALIR
VVQSMTQLVRRPPEVFEQEIRQHFSTGGWRLVNRIESWLETHALLEKSGYPDIGFPLFPL
SKGFIKSIRGVLTQFRAALLEAGMPECTEDK

Sequence of entity 3 (C), FASTA

>9MCB_3 Ubiquitin (chains C)
MQIFVKTLTGKTITLEVEPSDTIENVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLSDYN
IQKESTLHLVLRLRGG

Ligands and cofactors

ID	Name	Formula	Copies
AMP	Adenosine monophosphate	C10 H14 N5 O7 P	1

Primary citation

Cryo-EM structure of Human UBA1-UBE2O-Ub -Recruitment state 1. Chen, P.-T., Wu, K.-P. To be published.

Other PDB entries of the same protein (UniProt P22314 (AlphaFold model), which also has an AlphaFold model), best resolution first:

4P22 2.75 Å, Crystal Structure of N-terminal Fragments of E1
6DC6 3.14 Å, Crystal structure of human ubiquitin activating enzyme E1 (Uba1) in complex with ubiquitin
7PYV 3.27 Å, Crystal structure of human UBA6 in complex with the ubiquitin-like modifier FAT10
9MC5 3.29 Å, Cryo-EM structure of Human UBA1-UBE2O-Ub -Transthiolation state 3
9WD1 3.31 Å, Cryo-EM structure of Human UBA1-UBE2O-Ub -Recruitment state 3
9MC4 3.32 Å, Cryo-EM structure of Human UBA1-UBE2O-Ub -Transthiolation state 4
9MC6 3.32 Å, Cryo-EM structure of Human UBA1-UBE2O-Ub -Transthiolation state 2
9WD0 3.33 Å, Cryo-EM structure of Human UBA1-UBE2O-Ub -Recruitment state 2
9MC7 3.34 Å, Cryo-EM structure of Human UBA1-UBE2O-Ub -Recruitment state 4
9MC9 3.37 Å, Cryo-EM structure of Human UBA1-UBE2O-Ub -Transthiolation state 1

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