9HO5: Human Frataxin protein

Crystal Structure of the Human Frataxin protein in complex with a tailored Camelid Nanobody 4A7. Determined by X-ray diffraction at 1.5 Å resolution. Released 24 Dec 2025.

Method: X-ray diffraction
Resolution: 1.5 Å
Organisms: Homo sapiens, Lama glama
Chains: 2
Atoms: 2,048
Mol. weight: 28.91 kDa
Released: 24 Dec 2025

Explore 9HO5 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9HO5 contains 4 α-helices and 20 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: 2 helices, 8 β-strands

Element	Residues	Length	Sheet
α-helix	3-24	22
β-strand	31	1	1
β-strand	35-39	5	2
β-strand	42-46	5	2
β-strand	53-59	7	2
β-strand	64-69	6	2
β-strand	73-79	7	2
β-strand	84-86	3	2
β-strand	92	1	2
α-helix	93-105	13

Chain C: 2 helices, 12 β-strands

Element	Residues	Length	Sheet
β-strand	3-7	5	3
β-strand	10-12	3	1
β-strand	18-25	8	3
β-strand	34-39	6	1
β-strand	45-51	7	1
β-strand	57-59	3	1
β-strand	67-72	6	3
β-strand	77-82	6	3
α-helix	87-89	3
β-strand	91-97	7	1
α-helix	100-101	2
β-strand	102	1	4
β-strand	108	1	4
β-strand	114-118	5	1

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Frataxin mature form	A	protein	122	Homo sapiens	Q16595 (AlphaFold model)
Camelid Nanobody 4A7	C	protein	139	Lama glama

Sequence of entity 1 (A), FASTA

>9HO5_1 Frataxin mature form (chains A)
MLDETTYERLAEETLDSLAEFFEDLADKPYTFEDYDVSFGSGVLTVKLGGDLGTYVINKQ
TPNKQIWLSSPSSGPKRYDWTGKNWVYSHDGVSLHELLAAELTKALKTKLDLSSLAYSGK
DA

Sequence of entity 2 (C), FASTA

>9HO5_2 Camelid Nanobody 4A7 (chains C)
QVQLQESGGGSVQPGGSLRLSCVARGSVFSVWDMGWYRQVPGRGRHLVARLNDDGSTNYA
DSVKGRFTISRDNAKNTLYLQMNSLKPEDTAVYYCNAVPPIVTVNATDYWGQGTQVTVSS
AAAYPYDVPDYGSHHHHHH

Primary citation

Nanobodies as tools for studying human frataxin biology. Pignataro, M.F., Fernandez, N.B., Garay-Alvarez, A. et al. Commun Biol (2026) 9:181-181. DOI 10.1038/s42003-025-09458-x · PubMed

Other PDB entries of the same protein (UniProt Q16595 (AlphaFold model), which also has an AlphaFold model), best resolution first:

3T3L 1.15 Å, 1.15 A structure of human frataxin variant Q153A
3T3K 1.24 Å, 1.24 A Structure of Friedreich's ataxia frataxin variant Q148R
3S4M 1.3 Å, Crystal structure of wild-type human frataxin
3S5E 1.31 Å, Crystal structure of human frataxin variant W155R, one of the Friedreich's ataxia point…
3T3T 1.38 Å, 1.38 A structure of human frataxin variant Q148G
3S5D 1.5 Å, Crystal structure of human frataxin variant W155A
3S5F 1.5 Å, Crystal structure of human frataxin variant W155F
3T3X 1.57 Å, 1.57 A structure of Friedreich's ataxia frataxin variant R165C
3T3J 1.7 Å, 1.70 A structure of Friedreich's ataxia frataxin variant N146K
9HO4 1.76 Å, Crystal Structure of the Human Frataxin protein in complex with a tailored Camelid…
1EKG 1.8 Å, Mature human frataxin
9HO6 2.0 Å, Crystal Structure of the Human Frataxin protein in complex with a tailored Camelid…

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