9RJ4: Bub1 kinase domain

Bub1 kinase domain in complex with inhibitor LEI221. Determined by X-ray diffraction at 1.85 Å resolution. Released 24 Jun 2026.

Method: X-ray diffraction
Resolution: 1.85 Å
Organism: Homo sapiens
Chains: 2
Atoms: 5,865
Mol. weight: 85.06 kDa
Ligands: A1JG7, CA
Released: 24 Jun 2026

Explore 9RJ4 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9RJ4 contains 41 α-helices and 38 β-strands across 2 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: 21 helices, 19 β-strands

Element	Residues	Length	Sheet
α-helix	734-736	3
β-strand	737	1	1
α-helix	744-752	9
α-helix	758-760	3
β-strand	764-766	3	2
α-helix	770-773	4
β-strand	778-782	5	2
β-strand	785-796	12	2
β-strand	799-805	7	2
β-strand	817-823	7	2
α-helix	829-840	12
α-helix	843-848	6
β-strand	849	1	3
α-helix	850-851	2
β-strand	852-858	7	2
β-strand	861-866	6	2
β-strand	873	1	3
α-helix	874-881	8
α-helix	891-910	20
β-strand	913-914	2	4
α-helix	920-922	3
β-strand	923-925	3	3
α-helix	927-930	4
β-strand	942-944	3	3
β-strand	951-952	2	4
α-helix	953-955	3
β-strand	961	1	1
β-strand	962	1	5
α-helix	964-966	3
α-helix	971-973	3
α-helix	974-977	4
β-strand	982	1	5
α-helix	985-1000	16
β-strand	1006-1009	4	6
β-strand	1012-1015	4	6
α-helix	1019-1021	3
α-helix	1025-1036	12
α-helix	1044-1046	3
α-helix	1047-1061	15
α-helix	1066-1079	14

Chain B: 20 helices, 19 β-strands

Element	Residues	Length	Sheet
α-helix	734-736	3
β-strand	737	1	7
α-helix	744-752	9
α-helix	758-760	3
β-strand	764-766	3	8
α-helix	770-773	4
β-strand	778-782	5	8
β-strand	785-796	12	8
β-strand	799-805	7	8
β-strand	817-823	7	8
α-helix	829-840	12
α-helix	843-848	6
β-strand	849	1	9
α-helix	850-851	2
β-strand	852-857	6	8
β-strand	862-866	5	8
β-strand	873	1	9
α-helix	874-881	8
α-helix	891-910	20
β-strand	913-914	2	10
α-helix	920-922	3
β-strand	923-925	3	9
α-helix	927-930	4
β-strand	942-944	3	9
β-strand	951-952	2	10
α-helix	953-955	3
β-strand	961	1	7
β-strand	962	1	11
α-helix	964-966	3
α-helix	971-972	2
α-helix	974-977	4
β-strand	982	1	11
α-helix	985-1000	16
β-strand	1006-1009	4	12
β-strand	1012-1015	4	12
α-helix	1025-1036	12
α-helix	1044-1046	3
α-helix	1047-1061	15
α-helix	1066-1079	14

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Mitotic checkpoint serine/threonine-protein kinase BUB1	A, B	protein	364	Homo sapiens	O43683 (AlphaFold model)

Sequence of entity 1 (A, B), FASTA

>9RJ4_1 Mitotic checkpoint serine/threonine-protein kinase BUB1 (chains A, B)
GPGMSSLGTVDAPNFIVGNPWDDKLIFKLLSGLSKPVSSYPNTFEWQCKLPAIKPKTEFQ
LGSKLVYVHHLLGEGAFAQVYEATQGDLNDAKNKQKFVLKVQKPANPWEFYIGTQLMERL
KPSMQHMFMKFYSAHLFQNGSVLVGELYSYGTLLNAINLYKNTPEKVMPQGLVISFAMRM
LYMIEQVHDCEIIHGDIKPDNFILGNGFLEQDDEDDLSAGLALIDLGQSIDMKLFPKGTI
FTAKCETSGFQCVEMLSNKPWNYQIDYFGVAATVYCMLFGTYMKVKNEGGECKPEGLFRR
LPHLDMWNEFFHVMLNIPDCHHLPSLDLLRQKLKKVFQQHYTNKIRALRNRLIVLLLECK
RSRK

Ligands and cofactors

ID	Name	Formula	Copies
A1JG7	5-chloranyl-1-[[4-ethoxy-2,6-bis(fluoranyl)phenyl]methyl]-3-[5-methoxy-4-(1H-py…	C22 H19 Cl F2 N6 O3	2
CA	Calcium ion	Ca	2

Water and common crystallization additives (GOL) are not listed.

Primary citation

Bub1 kinase domain in complex with inhibitor LEI221. Konijnenberg, M.J. To be published.

Other PDB entries of the same protein (UniProt O43683 (AlphaFold model), which also has an AlphaFold model), best resolution first:

7B1F 1.75 Å, Orthorhombic P212121 Structure of Human Mad1 C-terminal Domain in Complex with…
6F7B 2.0 Å, Crystal structure of the human Bub1 kinase domain in complex with BAY 1816032
4QPM 2.2 Å, Structure of Bub1 kinase domain
9RJ2 2.3 Å, Bub1 kinase domain in complex with covalent inhibitor BM047
4R8Q 2.31 Å, Structure and substrate recruitment of the human spindle checkpoint kinase bub1
5DMZ 2.4 Å, Structure of human Bub1 kinase domain phosphorylated at Ser969
7B1H 2.4 Å, Monoclinic P21 Structure of Human Mad1 C-terminal Domain in Complex with Phosphorylated…
4A1G 2.6 Å, The crystal structure of the human Bub1 TPR domain in complex with the KI motif of Knl1
7B1J 2.9 Å, Orthorhombic P21212 Structure of Human Mad1 C-terminal Domain in Complex with…
2LAH Solution NMR Structure of Mitotic checkpoint serine/threonine-protein kinase BUB1…

Browse structure collections

About this viewer

MolViewer shows 9RJ4 directly in your browser with nothing to install. Switch between cartoon, ball-and-stick, spacefill and surface views, color by chain, secondary structure or B-factor, measure distances, angles and dihedrals, and share or embed the view.