9XZJ: F-box helicase 1

Cryo-EM structure of F-box helicase 1 (FBH1) bound to an SCF ubiquitin ligase complex and a 3-way DNA fork (consensus structure). Determined by electron microscopy at 3.13 Å resolution. Released 28 Jan 2026.

Method
Electron microscopy
Resolution
3.13 Å
Organisms
Homo sapiens, synthetic construct
Chains
8
Atoms
16,522
Mol. weight
270.79 kDa
Ligands
AGS, MG, ZN
Released
28 Jan 2026

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

Secondary structure: helices and β-sheets

9XZJ contains 110 α-helices and 43 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 C: 41 helices, 13 β-strands

ElementResiduesLengthSheet
α-helix17-3216
α-helix39-5315
α-helix78-10730
α-helix112-13625
α-helix138-1403
α-helix141-1455
α-helix146-1516
α-helix159-1679
α-helix168-1725
α-helix173-19220
α-helix198-21114
α-helix226-2283
α-helix229-2335
α-helix234-25421
α-helix257-27822
α-helix283-29513
α-helix297-2993
α-helix300-31314
α-helix316-32712
α-helix333-35523
α-helix356-3616
α-helix363-38422
α-helix389-40315
α-helix407-4126
α-helix417-43014
β-strand43111
α-helix439-45416
α-helix459-47618
β-strand47911
α-helix482-49615
α-helix498-52629
β-strand534-54182
α-helix554-5563
α-helix557-57317
β-strand577-58152
α-helix583-5853
β-strand587-59262
β-strand600-60232
α-helix605-6128
α-helix613-6153
β-strand619-62133
α-helix622-6298
α-helix633-64513
β-strand649-65133
β-strand668-67143
β-strand681-68332
α-helix686-6883
α-helix689-72234
β-strand724-72634
α-helix727-73812
α-helix746-75813
β-strand762-76434
α-helix7651
β-strand771-77444
Chain F: 59 helices, 26 β-strands
ElementResiduesLengthSheet
α-helix138-1403
α-helix143-1508
α-helix155-1606
α-helix162-1643
α-helix167-1748
α-helix180-18910
α-helix193-20513
α-helix215-22612
α-helix234-2418
α-helix247-25711
α-helix259-2624
α-helix270-28011
α-helix284-29411
α-helix297-2993
α-helix303-32321
α-helix329-34315
α-helix369-3768
β-strand384-38965
α-helix395-40511
β-strand411-41555
α-helix418-42710
β-strand432-43655
α-helix437-4415
α-helix442-4465
α-helix447-4515
β-strand45516
α-helix462-4687
α-helix4701
α-helix476-49116
α-helix499-5013
β-strand505-50737
β-strand513-51537
α-helix516-5172
α-helix518-53619
α-helix544-5463
β-strand54816
α-helix550-55910
β-strand569-57355
α-helix575-5773
α-helix580-5878
β-strand592-59765
α-helix599-6013
α-helix605-6073
α-helix612-6154
β-strand620-62455
β-strand62618
α-helix632-64615
β-strand65418
β-strand66119
β-strand670-67459
α-helix677-68812
α-helix693-6953
β-strand696-69839
α-helix707-71711
α-helix720-7267
α-helix733-7375
α-helix744-75411
α-helix757-76913
α-helix770-7723
α-helix773-78311
β-strand78419
α-helix788-7903
β-strand793-79759
α-helix798-8014
β-strand806-81169
α-helix816-8183
α-helix822-8276
α-helix833-8353
α-helix838-84912
β-strand851-85669
α-helix859-8679
β-strand873-877510
α-helix878-8814
β-strand888111
α-helix8961
β-strand897111
α-helix898-8992
β-strand904-908510
α-helix909-9102
β-strand911-912212
β-strand918-919212
β-strand922-924310
α-helix926-9338
α-helix934-9396
α-helix943-9475
Chain R: 0 helices, 1 β-strand
ElementResiduesLengthSheet
β-strand22-35142
Chain S: 10 helices, 3 β-strands
ElementResiduesLengthSheet
β-strand3-7513
β-strand13-17513
α-helix18-214
α-helix25-339
β-strand45-46213
α-helix52-6413
α-helix68-747
α-helix87-926
α-helix97-11014
α-helix113-12715
α-helix132-1398
α-helix147-15711
α-helix158-1603

Molecules and chains

MoleculeChainsTypeLengthOrganismUniProt
Cullin-1Cprotein776Homo sapiensQ13616 (AlphaFold model)
E3 ubiquitin-protein ligase RBX1Rprotein108Homo sapiensP62877 (AlphaFold model)
F-box DNA helicase 1Fprotein972Homo sapiensQ8NFZ0 (AlphaFold model)
S-phase kinase-associated protein 1Sprotein163Homo sapiensP63208 (AlphaFold model)
DNA (45-mer)XDNA45synthetic construct
DNA (5'-d(*cp*tp*gp*ap*cp*gp*cp*tp*tp*cp*cp*ap*tp*cp*gp*cp*tp*gp*tp*cp*tp*ap*g)-3')ADNA23synthetic construct
DNA (5'-d(*tp*cp*gp*cp*tp*ap*cp*cp*tp*tp*cp*gp*cp*ap*gp*tp*c)-3')BDNA17synthetic construct
DNA (45-mer)YDNA45synthetic construct
Sequence of entity 1 (C), FASTA
>9XZJ_1 Cullin-1 (chains C)
MSSTRSQNPHGLKQIGLDQIWDDLRAGIQQVYTRQSMAKSRYMELYTHVYNYCTSVHQSN
QARGAGVPPSKSKKGQTPGGAQFVGLELYKRLKEFLKNYLTNLLKDGEDLMDESVLKFYT
QQWEDYRFSSKVLNGICAYLNRHWVRRECDEGRKGIYEIYSLALVTWRDCLFRPLNKQVT
NAVLKLIEKERNGETINTRLISGVVQSYVELGLNEDDAFAKGPTLTVYKESFESQFLADT
ERFYTRESTEFLQQNPVTEYMKKAEARLLEEQRRVQVYLHESTQDELARKCEQVLIEKHL
EIFHTEFQNLLDADKNEDLGRMYNLVSRIQDGLGELKKLLETHIHNQGLAAIEKCGEAAL
NDPKMYVQTVLDVHKKYNALVMSAFNNDAGFVAALDKACGRFINNNAVTKMAQSSSKSPE
LLARYCDSLLKKSSKNPEEAELEDTLNQVMVVFKYIEDKDVFQKFYAKMLAKRLVHQNSA
SDDAEASMISKLKQACGFEYTSKLQRMFQDIGVSKDLNEQFKKHLTNSEPLDLDFSIQVL
SSGSWPFQQSCTFALPSELERSYQRFTAFYASRHSGRKLTWLYQLSKGELVTNCFKNRYT
LQASTFQMAILLQYNTEDAYTVQQLTDSTQIKMDILAQVLQILLKSKLLVLEDENANVDE
VELKPDTLIKLYLGYKNKKLRVNINVPMETEQKQEQETTHKNIEEDRKLLIQAAIVRIMK
MRKVLKHQQLLGEVLTQLSSRFKPRVPVIKKCIDILIEKEYLERVDGEKDTYSYLA
Sequence of entity 2 (R), FASTA
>9XZJ_2 E3 ubiquitin-protein ligase RBX1 (chains R)
MAAAMDVDTPSGTNSGAGKKRFEVKKWNAVALWAWDIVVDNCAICRNHIMDLCIECQANQ
ASATSEECTVAWGVCNHAFHFHCISRWLKTRQVCPLDNREWEFQKYGH
Sequence of entity 3 (F), FASTA
>9XZJ_3 F-box DNA helicase 1 (chains F)
SNAMAKSNSVGQDSCQDSEGDMIFPAESSCALPQEGSAGPGSPGSAPPSRKRSWSSEEES
NQATGTSRWDGVSKKAPRHHLSVPCTRPREARQEAEDSTSRLSAESGETDQDAGDVGPDP
IPDSYYGLLGTLPCQEALSHICSLPSEVLRHVFAFLPVEDLYWNLSLVCHLWREIISDPL
FIPWKKLYHRYLMNEEQAVSKVDGILSNCGIEKESDLCVLNLIRYTATTKCSPSVDPERV
LWSLRDHPLLPEAEACVRQHLPDLYAAAGGVNIWALVAAVVLLSSSVNDIQRLLFCLRRP
SSTVTMPDVTETLYCIAVLLYAMREKGINISNRIHYNIFYCLYLQENSCTQATKVKEEPS
VWPGKKTIQLTHEQQLILNHKMEPLQVVKIMAFAGTGKTSTLVKYAEKWSQSRFLYVTFN
KSIAKQAERVFPSNVICKTFHSMAYGHIGRKYQSKKKLNLFKLTPFMVNSVLAEGKGGFI
RAKLVCKTLENFFASADEELTIDHVPIWCKNSQGQRVMVEQSEKLNGVLEASRLWDNMRK
LGECTEEAHQMTHDGYLKLWQLSKPSLASFDAIFVDEAQDCTPAIMNIVLSQPCGKIFVG
DPHQQIYTFRGAVNALFTVPHTHVFYLTQSFRFGVEIAYVGATILDVCKRVRKKTLVGGN
HQSGIRGDAKGQVALLSRTNANVFDEAVRVTEGEFPSRIHLIGGIKSFGLDRIIDIWILL
QPEEERRKQNLVIKDKFIRRWVHKEGFSGFKRYVTAAEDKELEAKIAVVEKYNIRIPELV
QRIEKCHIEDLDFAEYILGTVHKAKGLEFDTVHVLDDFVKVPCARHNLPQLPHFRVESFS
EDEWNLLYVAVTRAKKRLIMTKSLENILTLAGEYFLQAELTSNVLKTGVVRCCVGQCNNA
IPVDTVLTMKKLPITYSNRKENKGGYLCHSCAEQRIGPLAFLTASPEQVRAMERTVENIV
LPRHEALLFLVF
Sequence of entity 4 (S), FASTA
>9XZJ_4 S-phase kinase-associated protein 1 (chains S)
MPSIKLQSSDGEIFEVDVEIAKQSVTIKTMLEDLGMDDEGDDDPVPLPNVNAAILKKVIQ
WCTHHKDDPPPPEDDENKEKRTDDIPVWDQEFLKVDQGTLFELILAANYLDIKGLLDVTC
KTVANMIKGKTPEEIRKTFNIKNDFTEEEEAQVRKENQWCEEK
Sequence of entity 5 (X), FASTA
>9XZJ_5 DNA (45-MER) (chains X)
GACTGCGAAGGTAGCGACAGATCCCCTGACGAACTGAGTCCTGAG
Sequence of entity 6 (A), FASTA
>9XZJ_6 DNA (5'-D(*CP*TP*GP*AP*CP*GP*CP*TP*TP*CP*CP*AP*TP*CP*GP*CP*TP*GP*TP*CP*TP*AP*G)-3') (chains A)
CTGACGCTTCCATCGCTGTCTAG
Sequence of entity 7 (B), FASTA
>9XZJ_7 DNA (5'-D(*TP*CP*GP*CP*TP*AP*CP*CP*TP*TP*CP*GP*CP*AP*GP*TP*C)-3') (chains B)
TCGCTACCTTCGCAGTC
Sequence of entity 8 (Y), FASTA
>9XZJ_8 DNA (45-MER) (chains Y)
CTCAGGACTCAGTTCGTCAGCCCTAGACAGCGATGGAAGCGTCAG

Ligands and cofactors

IDNameFormulaCopies
AGSPhosphothiophosphoric acid-adenylate esterC10 H16 N5 O12 P3 S1
MGMagnesium ionMg1
ZNZinc ionZn1

Primary citation

Structural basis for fork reversal and RAD51 regulation by the SCF ubiquitin ligase complex of F-box helicase 1. Greer, B.H., Mendia-Garcia, J., Mullins, E.A. et al. Nat Commun (2026) 17. DOI 10.1038/s41467-026-68752-2 · PubMed

Other PDB entries of the same protein (UniProt Q13616 (AlphaFold model), which also has an AlphaFold model), best resolution first:

Browse structure collections

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