9PXO: Fem-1 homolog B

Name: PDB 9PXO: Fem-1 homolog B (FEM1B) in complex with VU0023775
Published: 2025-11-26
License: https://creativecommons.org/publicdomain/zero/1.0/
Keywords: ligase

Fem-1 homolog B (FEM1B) in complex with VU0023775. Determined by X-ray diffraction at 3.05 Å resolution. Released 26 Nov 2025.

Method: X-ray diffraction
Resolution: 3.05 Å
Organism: Homo sapiens
Chains: 2
Atoms: 5,032
Mol. weight: 79.09 kDa
Ligands: A1CMX
Released: 26 Nov 2025

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

Secondary structure: helices and β-sheets

9PXO contains 42 α-helices and 8 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, 4 β-strands

Element	Residues	Length	Sheet
α-helix	2-13	12
α-helix	17-23	7
α-helix	29-37	9
β-strand	40-41	2	1
β-strand	46-47	2	1
α-helix	49-55	7
α-helix	59-66	8
β-strand	77-81	5	1
β-strand	84-89	6	1
α-helix	91-98	8
α-helix	101-109	9
α-helix	124-131	8
α-helix	134-142	9
α-helix	157-164	8
α-helix	167-175	9
α-helix	190-197	8
α-helix	200-208	9
α-helix	222-228	7
α-helix	232-239	8
α-helix	247-259	13
α-helix	263-265	3
α-helix	270-281	12
α-helix	295-298	4
α-helix	311-315	5
α-helix	321-335	15

Chain B: 21 helices, 4 β-strands

Element	Residues	Length	Sheet
α-helix	4-14	11
α-helix	17-23	7
α-helix	29-36	8
β-strand	40-41	2	2
β-strand	46-47	2	2
α-helix	49-55	7
α-helix	59-66	8
β-strand	78-81	4	3
β-strand	84-87	4	3
α-helix	91-98	8
α-helix	101-109	9
α-helix	124-131	8
α-helix	134-141	8
α-helix	157-164	8
α-helix	167-175	9
α-helix	190-197	8
α-helix	200-208	9
α-helix	222-228	7
α-helix	232-238	7
α-helix	250-262	13
α-helix	270-280	11
α-helix	295-297	3
α-helix	311-314	4
α-helix	317-319	3
α-helix	321-335	15

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Protein fem-1 homolog B	A, B	protein	357	Homo sapiens	Q9UK73 (AlphaFold model)

Sequence of entity 1 (A, B), FASTA

>9PXO_1 Protein fem-1 homolog B (chains A, B)
GHMEGLAGYVYKAASEGKVLTLAALLLNRSESDIRYLLGYVSQQGGQRSTPLIIAARNGH
AKVVRLLLEHYRVQTQQTGTVRFDGYVIDGATALWCAAGAGHFEVVKLLVSHGANVNHTT
VTNSTPLRAACFDGRLDIVKYLVENNANISIANKYDNTCLMIAAYKGHTDVVRYLLEQRA
DPNAKAHCGATALHFAAEAGHIDIVKELIKWRAAIVVNGHGMTPLKVAAESCKADVVELL
LSHADCDRRSRIEALELLGASFANDRENYDIIKTYHYLYLAMLERFQDGDNILEKEVLPP
IHAYGNRTECRNPQELESIRQDRDALHMEGLIVRERILGGGGSGGGSKKRLLLGLDR

Ligands and cofactors

ID	Name	Formula	Copies
A1CMX	2-tert-butyl-1,3-dioxo-2,3-dihydro-1H-isoindole-5-carboxylic acid	C13 H13 N O4	2

Primary citation

Nuclear Magnetic Resonance-based fragment screen of the E3 ligase Fem-1 homolog B. Katinas, J.M., Amporndanai, K., Taylor, A.J. et al. Protein Sci (2025) 34:e70365-e70365. DOI 10.1002/pro.70365 · PubMed

Other PDB entries of the same protein (UniProt Q9UK73 (AlphaFold model), which also has an AlphaFold model), best resolution first:

9PW8 2.8 Å, Fem-1 homolog B (FEM1B) in complex with VU0417412
7EL6 2.8 Å, Structure of SMCR8 bound FEM1B
9PQA 2.9 Å, Fem-1 homolog B (FEM1B) in complex with VU0432623
9PQ9 2.93 Å, Fem-1 homolog B (FEM1B) in complex with VU0421763
9PWJ 3.0 Å, Fem-1 homolog B (FEM1B) in complex with VU0081201
9PXP 3.0 Å, Fem-1 homolog B (FEM1B) in complex with VU0416476
9PQE 3.1 Å, Fem-1 homolog B (FEM1B) in complex with VU0412674
6LBF 3.25 Å, Crystal structure of FEM1B
8WQF 3.27 Å, cryo-EM structure of CUL2-RBX1-ELOB-ELOC-FEM1B bound with the C-degron of CUX1…
8WQB 3.37 Å, Cryo-EM structure of CUL2-RBX1-ELOB-ELOC-FEM1B bound with the C-degron of CCDC89…
8WQE 3.38 Å, Cryo-EM structure of CUL2-RBX1-ELOB-ELOC-FEM1B bound with the C-degron of CUX1…
8WQA 3.39 Å, Cryo-EM structure of CUL2-RBX1-ELOB-ELOC-FEM1B bound with the C-degron of CCDC89…

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