9HO6: Human Frataxin protein

Crystal Structure of the Human Frataxin protein in complex with a tailored Camelid Nanobody 16C10. Determined by X-ray diffraction at 2.0 Å resolution. Released 24 Dec 2025.

Method: X-ray diffraction
Resolution: 2.0 Å
Organisms: Homo sapiens, Lama glama
Chains: 4
Atoms: 4,011
Mol. weight: 57.55 kDa
Released: 24 Dec 2025

Explore 9HO6 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9HO6 contains 12 α-helices and 42 β-strands across 4 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: 3 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
α-helix	60-62	3
β-strand	64-69	6	2
β-strand	73-79	7	2
β-strand	84-86	3	2
β-strand	91-92	2	2
α-helix	93-105	13

Chain B: 2 helices, 9 β-strands

Element	Residues	Length	Sheet
α-helix	3-24	22
β-strand	31	1	5
β-strand	35-39	5	7
β-strand	42-46	5	7
β-strand	53-59	7	7
β-strand	64-69	6	7
β-strand	73-77	5	7
β-strand	78-79	2	8
β-strand	84-86	3	8
β-strand	91-92	2	8
α-helix	93-105	13

Chain C: 3 helices, 12 β-strands

Element	Residues	Length	Sheet
β-strand	3-7	5	9
β-strand	10-12	3	1
β-strand	18-25	8	9
α-helix	27-31	5
β-strand	34-39	6	1
β-strand	46-51	6	1
β-strand	57-59	3	1
β-strand	67-72	6	9
β-strand	77-82	6	9
α-helix	87-89	3
β-strand	91-97	7	1
β-strand	102	1	10
β-strand	108	1	10
β-strand	114-118	5	1
α-helix	120-122	3

Chain D: 4 helices, 13 β-strands

Element	Residues	Length	Sheet
β-strand	3-7	5	3
β-strand	11-12	2	4
β-strand	18-25	8	3
α-helix	27-31	5
β-strand	34-39	6	5
α-helix	44-45	2
β-strand	46-51	6	5
β-strand	57-59	3	5
β-strand	67-72	6	3
β-strand	77-82	6	3
α-helix	87-89	3
β-strand	91-97	7	5
β-strand	102	1	6
β-strand	108	1	6
β-strand	114-116	3	5
β-strand	117-118	2	4
α-helix	120-122	3

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Frataxin mature form	A, B	protein	122	Homo sapiens	Q16595 (AlphaFold model)
Camelid Nanobody 16C10	C, D	protein	139	Lama glama

Sequence of entity 1 (A, B), FASTA

>9HO6_1 Frataxin mature form (chains A, B)
MLDETTYERLAEETLDSLAEFFEDLADKPYTFEDYDVSFGSGVLTVKLGGDLGTYVINKQ
TPNKQIWLSSPSSGPKRYDWTGKNWVYSHDGVSLHELLAAELTKALKTKLDLSSLAYSGK
DA

Sequence of entity 2 (C, D), FASTA

>9HO6_2 Camelid Nanobody 16C10 (chains C, D)
QVQLQESGGGLVQPGGSLRLSCAATGSIFSINNMGWYRQPPGKGRHLVARLNDDGSTNYA
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
9HO5 1.5 Å, Crystal Structure of the Human Frataxin protein in complex with a tailored Camelid…
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

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