9S2I: 14-3-3 protein sigma

Ternary structure of 14-3-3, CRAF R256S NS mutant phosphopeptide (pS259), and compound 78 (1124378). Determined by X-ray diffraction at 1.67 Å resolution. Released 22 Apr 2026.

Method: X-ray diffraction
Resolution: 1.67 Å
Organism: Homo sapiens
Chains: 2
Atoms: 2,220
Mol. weight: 28.32 kDa
Ligands: WQN, MG
Released: 22 Apr 2026

Explore 9S2I in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9S2I contains 15 α-helices and 0 β-strands across 1 chain. 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: 15 helices, 0 β-strands

Element	Residues	Length
α-helix	3-15	13
α-helix	19-31	13
α-helix	34-37	4
α-helix	38-69	32
α-helix	74-76	3
α-helix	80-102	23
α-helix	103-107	5
α-helix	108-110	3
α-helix	114-134	21
α-helix	140-161	22
α-helix	167-178	12
α-helix	179-183	5
α-helix	187-202	16
α-helix	205-207	3
α-helix	210-230	21

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
14-3-3 protein sigma	A	protein	236	Homo sapiens	P31947 (AlphaFold model)
RAF proto-oncogene serine/threonine-protein kinase	P	protein	11	Homo sapiens	P04049 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>9S2I_1 14-3-3 protein sigma (chains A)
GAMGSMERASLIQKAKLAEQAERYEDMAAFMKGAVEKGEELSCEERNLLSVAYKNVVGGQ
RAAWRVLSSIEQKSNEEGSEEKGPEVREYREKVETELQGVCDTVLGLLDSHLIKEAGDAE
SRVFYLKMKGDYYRYLAEVATGDDKKRIIDSARSAYQEAMDISKKEMPPTNPIRLGLALN
FSVFHYEIANSPEEAISLAKTTFDEAMADLHTLSEDSYKDSTLIMQLLRDNLTLWT

Sequence of entity 2 (P), FASTA

>9S2I_2 RAF proto-oncogene serine/threonine-protein kinase (chains P)
QSSTSTPNVHM

Ligands and cofactors

ID	Name	Formula	Copies
WQN	1-[8-(4-bromophenyl)sulfonyl-5-oxa-2,8-diazaspiro[3.5]nonan-2-yl]-2-chloranyl-e…	C14 H16 Br Cl N2 O4 S	1
MG	Magnesium ion	Mg	2

Water and common crystallization additives (CL) are not listed.

Primary citation

Restoring the 14-3-3/CRAF regulatory interaction in Noonan syndrome using molecular glues. Virta, J.M., Vickery, H.R., Konstantinidou, M. et al. Proc Natl Acad Sci U S A (2026) 123:e2602101123-e2602101123. DOI 10.1073/pnas.2602101123 · PubMed

Other PDB entries of the same protein (UniProt P31947 (AlphaFold model), which also has an AlphaFold model), best resolution first:

3IQU 1.05 Å, Crystal Structure of human 14-3-3 sigma in Complex with Raf1 peptide (6mer)
7AZ2 1.08 Å, 14-3-3 sigma with Pin1 binding site pS72 and covalently bound LvD1014
6HMT 1.1 Å, Ternary complex of Estrogen Receptor alpha peptide and 14-3-3 sigma C42 mutant bound to…
7BAA 1.1 Å, Cys-42-tethered stabilizer 12 of 14-3-3(sigma)/ERa PPI
8BZC 1.1 Å, co-soaked stabilizers for ERa - 14-3-3 interaction (884_AZ244)
8BZW 1.1 Å, Co-soaked stabilizers for ERa - 14-3-3 interaction (844_AZ210)
8C04 1.1 Å, Co-soaked stabilizers for ERa - 14-3-3 interaction (884_AZ354)
9GG8 1.1 Å, Crystal structure of 14-3-3 sigma dC - C38N in complex with Tau pS214 peptide and…
8ANC 1.11 Å, 14-3-3 sigma sirtuin-3 phospho-peptide complex
6Y1J 1.13 Å, 14-3-3 sigma in complex with IkappaBalpha pS63 peptide
6G6X 1.13 Å, 14-3-3sigma in complex with a P129beta3P mutated YAP pS127 phosphopeptide
6NV2 1.13 Å, 14-3-3 sigma with RelA/p65 binding site pS45 in complex with DP005

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