9PIU: Synthetic Fab

Crystal structure of a synthetic Fab (2C) in complex with the FRB domain of mTOR. Determined by X-ray diffraction at 2.18 Å resolution. Released 17 Jun 2026.

Method: X-ray diffraction
Resolution: 2.18 Å
Organism: Homo sapiens
Chains: 3
Atoms: 4,550
Mol. weight: 57.88 kDa
Released: 17 Jun 2026

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

Secondary structure: helices and β-sheets

9PIU contains 22 α-helices and 46 β-strands across 3 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 D: 6 helices, 0 β-strands

Element	Residues	Length
α-helix	2-15	14
α-helix	16-20	5
α-helix	21	1
α-helix	24-39	16
α-helix	45-71	27
α-helix	74-91	18

Chain H: 8 helices, 24 β-strands

Element	Residues	Length	Sheet
β-strand	3-7	5	1
β-strand	11-12	2	2
β-strand	18-25	8	1
α-helix	29-31	3
β-strand	33-39	7	3
β-strand	46-52	7	3
β-strand	57-60	4	3
β-strand	68-73	6	1
β-strand	78-83	6	1
α-helix	88-90	3
β-strand	92-99	8	3
β-strand	110	1	4
β-strand	116-117	2	3
β-strand	121-123	3	3
β-strand	124-125	2	2
β-strand	131	1	5
α-helix	132-133	2
β-strand	134-138	5	6
α-helix	139-141	3
β-strand	149-159	11	6
β-strand	160	1	5
β-strand	165-168	4	7
α-helix	169-171	3
β-strand	173	1	7
β-strand	177-179	3	6
α-helix	180-182	3
β-strand	183-184	2	6
β-strand	190-199	10	6
α-helix	200-202	3
β-strand	208-214	7	7
α-helix	215-217	3
β-strand	219-225	7	7

Chain L: 8 helices, 22 β-strands

Element	Residues	Length	Sheet
β-strand	6-8	3	8
β-strand	11-14	4	9
β-strand	20-25	6	8
β-strand	32	1	4
β-strand	34-39	6	9
β-strand	46-50	5	9
β-strand	54-55	2	9
α-helix	56	1
β-strand	63-68	6	8
β-strand	71-76	6	8
α-helix	81-83	3
β-strand	86-93	8	9
β-strand	96-99	4	9
β-strand	103-107	5	9
β-strand	112	1	10
α-helix	113-114	2
β-strand	115-119	5	11
α-helix	120-122	3
α-helix	123-127	5
β-strand	130-140	11	11
β-strand	141	1	10
β-strand	146-151	6	12
β-strand	154-155	2	12
α-helix	156	1
β-strand	160-164	5	11
α-helix	165-168	4
β-strand	174-183	10	11
α-helix	184-188	5
β-strand	192-199	8	12
β-strand	202-209	8	12

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Heavy chain	H	protein	228	Homo sapiens
Light chain	L	protein	206	Homo sapiens
Serine/threonine-protein kinase mTOR	D	protein	92	Homo sapiens	P42345 (AlphaFold model)

Sequence of entity 1 (H), FASTA

>9PIU_1 Heavy chain (chains H)
EVQLVESGGGLVQPGGSLRLSCAASGFNVYYSSIHWVRQAPGKGLEWVASISPYSGSTYY
ADSVKGRFTISADTSKNTAYLQMNSLRAEDTAVYYCARSWSYAVLPKQGSWMGMDYWGQG
TLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTF
PAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPK

Sequence of entity 2 (L), FASTA

>9PIU_2 Light chain (chains L)
MTQSPSSLSASVGDRVTITCRASQSVSSAVAWYQQKPGKAPKLLIYSASSLYSGVPSRFS
GSRSGTDFTLTISSLQPEDFATYYCQQWMEYLITFGQGTKVEIKRTVAAPSVFIFPPSDS
QLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSK
ADYEKHKVYACEVTQGTTSVTKSFNR

Sequence of entity 3 (D), FASTA

>9PIU_3 Serine/threonine-protein kinase mTOR (chains D)
ILWHEMWHEGLEEASRLYFGERNVKGMFEVLEPLHAMMERGPQTLKETSFNQAYGRDLME
AQEWCRKYMKSGNVKDLTQAWDLYYHVFRRIS

Primary citation

Crystal structure of a synthetic Fab (2C) in complex with the FRB domain of mTOR. O'Leary, K.M., Slezak, T., Le, D.A. et al. To be published.

Other PDB entries of the same protein (UniProt P42345 (AlphaFold model), which also has an AlphaFold model), best resolution first:

4DRI 1.45 Å, Co-crystal structure of the PPIase domain of FKBP51, Rapamycin and the FRB fragment of…
9DBO 1.55 Å, Crystal structure of a synthetic Fab (R3E9) in complex with the FRB domain of mTOR
5GPG 1.67 Å, Co-crystal structure of the FK506 binding domain of human FKBP25, Rapamycin and the FRB…
5WBH 1.75 Å, Structure of the FRB domain of mTOR bound to a substrate recruitment peptide of S6K1
4DRJ 1.8 Å, o-crystal structure of the PPIase domain of FKBP52, Rapamycin and the FRB fragment of mTOR
3FAP 1.85 Å, Atomic structures of the rapamycin analogs in complex with both human FKBP12 and frb…
8PPZ 1.85 Å, Co-crystal structure of FKBP12, compound 7 and the FRB fragment of mTOR
8XI9 1.85 Å, Crystal structure of FRB-FKBP fusion protein in complex with rapamycin
9PIW 1.9 Å, Crystal structure of a synthetic Fab (1A) in complex with the FRB domain of mTOR
9DL0 2.0 Å, Crystal structure of a synthetic Fab (R3H8) in complex with the FRB domain of mTOR
9PJ1 2.05 Å, Crystal structure of a synthetic Fab (4R) in complex with the ternary assembly of…
1NSG 2.2 Å, The structure of the immunophilin-immunosuppressant FKBP12-rapamycin complex interacting…

Browse structure collections

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