9CX2: HLA-A*03:01 L156Q mutant

Crystal structure of HLA-A*03:01 L156Q mutant in complex with a mutant PIK3CA peptide. Determined by X-ray diffraction at 2.3 Å resolution. Released 4 Feb 2026.

Method: X-ray diffraction
Resolution: 2.3 Å
Organism: Homo sapiens
Chains: 3
Atoms: 3,435
Mol. weight: 44.5 kDa
Released: 4 Feb 2026

Explore 9CX2 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9CX2 contains 14 α-helices and 30 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: 10 helices, 19 β-strands

Element	Residues	Length	Sheet
β-strand	3-12	10	1
α-helix	20	1
β-strand	21-28	8	1
β-strand	31-37	7	1
β-strand	46-47	2	1
α-helix	50-52	3
α-helix	57-84	28
β-strand	94-103	10	1
β-strand	109-118	10	1
β-strand	121-126	6	1
β-strand	133-135	3	1
α-helix	138-149	12
α-helix	152-158	7
α-helix	159-163	5
α-helix	164-174	11
β-strand	183	1	2
α-helix	184-185	2
β-strand	186-193	8	3
β-strand	198-208	11	3
β-strand	209	1	2
β-strand	214-219	6	4
β-strand	223	1	4
β-strand	229-230	2	3
α-helix	231-233	3
β-strand	234-235	2	3
β-strand	241-250	10	3
α-helix	254-256	3
β-strand	257-262	6	4
β-strand	270-272	3	4

Chain B: 4 helices, 11 β-strands

Element	Residues	Length	Sheet
β-strand	4	1	5
α-helix	5-6	2
β-strand	7-12	6	6
β-strand	22-31	10	6
β-strand	32	1	5
β-strand	37-42	6	7
β-strand	45-46	2	7
α-helix	47	1
β-strand	51-52	2	6
α-helix	53-55	3
β-strand	56-57	2	6
β-strand	63-71	9	6
β-strand	79-84	6	7
α-helix	91	1
β-strand	92-95	4	7

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
HLA class I histocompatibility antigen, A alpha chain	A	protein	274	Homo sapiens	P04439 (AlphaFold model)
Beta-2-microglobulin	B	protein	100	Homo sapiens	P61769 (AlphaFold model)
Mutant PIK3CA peptide	C	protein	9	Homo sapiens	P42336 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>9CX2_1 HLA class I histocompatibility antigen, A alpha chain (chains A)
GSHSMRYFFTSVSRPGRGEPRFIAVGYVDDTQFVRFDSDAASQRMEPRAPWIEQEGPEYW
DQETRNVKAQSQTDRVDLGTLRGYYNQSEAGSHTIQIMYGCDVGSDGRFLRGYRQDAYDG
KDYIALNEDLRSWTAADMAAQITKRKWEAAHEAEQQRAYLDGTCVEWLRRYLENGKETLQ
RTDPPKTHMTHHPISDHEATLRCWALGFYPAEITLTWQRDGEDQTQDTELVETRPAGDGT
FQKWAAVVVPSGEEQRYTCHVQHEGLPKPLTLRW

Sequence of entity 2 (B), FASTA

>9CX2_2 Beta-2-microglobulin (chains B)
MIQRTPKIQVYSRHPAENGKSNFLNCYVSGFHPSDIEVDLLKNGERIEKVEHSDLSFSKD
WSFYLLYYTEFTPTEKDEYACRVNHVTLSQPKIVKWDRDM

Sequence of entity 3 (C), FASTA

>9CX2_3 Mutant PIK3CA peptide (chains C)
ALHGGWTTK

Primary citation

HLA micropolymorphisms confine neoantigen conformational adaptability and guide T cell receptor selectivity. Ma, J., Ayres, C.M., Brambley, C.A. et al. Proc Natl Acad Sci U S A (2026) 123:e2602949123-e2602949123. DOI 10.1073/pnas.2602949123 · PubMed

Other PDB entries of the same protein (UniProt P04439 (AlphaFold model), which also has an AlphaFold model), best resolution first:

3MRE 1.1 Å, Crystal Structure of MHC class I HLA-A2 molecule complexed with EBV bmlf1-280-288…
3D25 1.3 Å, Crystal structure of HA-1 minor histocompatibility antigen bound to human class I MHC…
3MRG 1.3 Å, Crystal Structure of MHC class I HLA-A2 molecule complexed with HCV NS3-1073-1081…
6JOZ 1.35 Å, Crystal structure of BRLF peptide from EBV in complex with HLA-A1101.
5C0G 1.37 Å, HLA-A02 carrying YLGGPDFPTI
5N1Y 1.39 Å, HLA-A02 carrying MVWGPDPLYV
1I4F 1.4 Å, Crystal structure of HLA-A*0201/MAGE-A4-peptide complex
1OGA 1.4 Å, A structural basis for immunodominant human T-cell receptor recognition.
3MRB 1.4 Å, Crystal Structure of MHC class I HLA-A2 molecule complexed with HCMV pp65-495-503…
3MRK 1.4 Å, Crystal Structure of MHC class I HLA-A2 molecule complexed with AFP137 nonapeptide
6J2A 1.4 Å, The structure of HLA-A*3003/NP44
1X7Q 1.45 Å, Crystal structure of HLA-A*1101 with sars nucleocapsid peptide

Browse structure collections

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