9E2T: 21h10

Structure of a de novo designed interleukin-21 mimetic complex with IL-21R and IL-2Rg. Determined by X-ray diffraction at 2.28 Å resolution. Released 24 Sept 2025.

Method: X-ray diffraction
Resolution: 2.28 Å
Organisms: synthetic construct, Homo sapiens
Chains: 10
Atoms: 13,255
Mol. weight: 197.5 kDa
Ligands: NAG
Released: 24 Sept 2025

Explore 9E2T in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9E2T contains 68 α-helices and 102 β-strands across 10 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: 4 helices, 0 β-strands

Element	Residues	Length
α-helix	2-22	21
α-helix	29-48	20
α-helix	57-77	21
α-helix	83-98	16

Chain B: 10 helices, 18 β-strands

Element	Residues	Length	Sheet
β-strand	4-8	5	1
β-strand	13-19	7	1
α-helix	25-26	2
β-strand	27-32	6	2
β-strand	45-48	4	2
β-strand	49-53	5	1
β-strand	57-63	7	1
α-helix	66-68	3
β-strand	74-80	7	2
β-strand	87-94	8	2
α-helix	95-97	3
β-strand	99	1	1
α-helix	101-104	4
β-strand	105-111	7	3
β-strand	115-120	6	3
α-helix	122-124	3
α-helix	126-131	6
β-strand	135-143	9	4
β-strand	147	1	5
α-helix	151-152	2
β-strand	153-157	5	4
β-strand	163-166	4	3
α-helix	168-170	3
β-strand	176-185	10	4
α-helix	186	1
β-strand	193	1	1
α-helix	197-201	5
β-strand	202-205	4	4

Chain C: 7 helices, 16 β-strands

Element	Residues	Length	Sheet
α-helix	54-60	7
β-strand	61-65	5	6
β-strand	69-73	5	6
β-strand	86-91	6	7
β-strand	100-101	2	7
β-strand	105-107	3	6
β-strand	112-118	7	6
α-helix	119-121	3
α-helix	127	1
β-strand	128-133	6	7
β-strand	141-146	6	7
α-helix	148-150	3
β-strand	152-153	2	6
α-helix	154-157	4
β-strand	158-164	7	8
β-strand	170-175	6	8
α-helix	180-182	3
β-strand	183-191	9	9
β-strand	198-202	5	9
β-strand	207-209	3	8
β-strand	219-227	9	9
α-helix	239-243	5
β-strand	244-246	3	9

Chain D: 4 helices, 0 β-strands

Element	Residues	Length
α-helix	2-22	21
α-helix	30-48	19
α-helix	58-76	19
α-helix	81-98	18

Chain E: 9 helices, 17 β-strands

Element	Residues	Length	Sheet
α-helix	1-3	3
β-strand	4-8	5	10
β-strand	13-19	7	10
α-helix	25-26	2
β-strand	27-32	6	11
β-strand	45-48	4	11
β-strand	49-53	5	10
β-strand	57-63	7	10
α-helix	66-68	3
β-strand	74-80	7	11
β-strand	87-94	8	11
α-helix	95-97	3
β-strand	99	1	10
α-helix	101-104	4
β-strand	105-111	7	12
β-strand	115-120	6	12
β-strand	135-143	9	13
α-helix	151-152	2
β-strand	153-157	5	13
β-strand	163-166	4	12
α-helix	168-170	3
β-strand	176-185	10	13
α-helix	186	1
β-strand	193	1	10
α-helix	195-201	7
β-strand	202-205	4	13

Chain F: 8 helices, 16 β-strands

Element	Residues	Length	Sheet
α-helix	53-60	8
β-strand	61-65	5	14
β-strand	69-73	5	14
β-strand	86-91	6	15
α-helix	99	1
β-strand	100-101	2	15
α-helix	102	1
β-strand	105-108	4	14
β-strand	111-118	8	14
α-helix	119-121	3
β-strand	128-133	6	15
β-strand	141-146	6	15
α-helix	148-150	3
β-strand	152-153	2	14
α-helix	154-157	4
β-strand	158-164	7	16
β-strand	170-175	6	16
α-helix	180-182	3
β-strand	183-191	9	17
β-strand	198-202	5	17
β-strand	207-209	3	16
β-strand	218-227	10	17
α-helix	237-243	7
β-strand	244-247	4	17

Chain G: 4 helices, 0 β-strands

Element	Residues	Length
α-helix	3-22	20
α-helix	30-49	20
α-helix	58-77	20
α-helix	81-98	18

Chain H: 9 helices, 18 β-strands

Element	Residues	Length	Sheet
β-strand	4-8	5	18
β-strand	13-19	7	18
α-helix	25-26	2
β-strand	27-32	6	19
β-strand	45-48	4	19
β-strand	49-53	5	18
β-strand	57-63	7	18
α-helix	66-68	3
β-strand	74-80	7	19
β-strand	87-94	8	19
α-helix	95-97	3
β-strand	99	1	18
α-helix	101-104	4
β-strand	105-111	7	20
β-strand	115-120	6	20
α-helix	126-128	3
β-strand	135-143	9	21
β-strand	147	1	5
α-helix	151-152	2
β-strand	153-157	5	21
β-strand	163-166	4	20
α-helix	168-170	3
β-strand	176-185	10	21
α-helix	186	1
β-strand	193	1	18
α-helix	195-201	7
β-strand	202-205	4	21

2 more chain groups are not listed. Open the entry in the viewer and use the sequence panel to see them.

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
21h10	A, D, G, I	protein	102	synthetic construct
Interleukin-21 receptor	B, E, H, J	protein	212	Homo sapiens	Q9HBE5 (AlphaFold model)
Cytokine receptor common subunit gamma	C, F	protein	203	Homo sapiens	P31785 (AlphaFold model)

Sequence of entity 1 (A, D, G, I), FASTA

>9E2T_1 21h10 (chains A, D, G, I)
DEEELKEIMKEAAECARKELEKLDNTDEDTRWLKITLKKIVRMANRIVRMREREADSKRF
EIRMRGLIDIADHVKREFASEDLKEVMERAKSAAQKALGRWL

Sequence of entity 2 (B, E, H, J), FASTA

>9E2T_2 Interleukin-21 receptor (chains B, E, H, J)
ADPCPDLVCYTDYLQTVICILEMWNLHPSTLTLTWQDQYEELKDEATSCSLHRSAHNATH
ATYTCHMDVFHFMADDIFSVQITDQSGQYSQECGSFLLAESIKPAPPFDVTVTFSGQYQI
SWRSDYEDPAFYMLKGKLQYELQYRNRGDPWAVSPRRKLISVDSRSVSLLPLEFRKDSSY
ELQVRAGPMPGSSYQGTWSEWSDPVIFQTQSE

Sequence of entity 3 (C, F), FASTA

>9E2T_3 Cytokine receptor common subunit gamma (chains C, F)
ADPLPLPEVQCFVFNVEYMNCTWNSSSEPQPTNLTLHYWYKNSDNDKVQKCSHYLFSEEI
TSGCQLQKKEIHLYQTFVVQLQDPREPRRQATQMLKLQNLVIPWAPENLTLHKLSESQLE
LNWNNRFLNHCLEHLVQYRTDWDHSWTEQSVDYRHKFSLPSVDGQKRYTFRVRSRFNPLC
GSAQHWSEWSHPIHWGSNTSKEN

Ligands and cofactors

ID	Name	Formula	Copies
NAG	2-acetamido-2-deoxy-beta-D-glucopyranose	C8 H15 N O6	9

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

Primary citation

Design of a potent interleukin-21 mimic for cancer immunotherapy. Chun, J.H., Lim, B.S., Roy, S. et al. Sci Immunol (2025) 10:eadx1582-eadx1582. DOI 10.1126/sciimmunol.adx1582 · PubMed

Other PDB entries of the same protein (UniProt Q9HBE5 (AlphaFold model), which also has an AlphaFold model), best resolution first:

6PLH 1.6 Å, FAB fragment complexed with C-mannosylated tryptophan peptide
7KQ7 2.2 Å, Crystal structure of IL21R in complex with an antibody Fab fragment
4NZD 2.75 Å, Interleukin 21 receptor
3TGX 2.8 Å, IL-21:IL21R complex
8ENT 2.83 Å, Interleukin-21 signaling complex with IL-21R and IL-2Rg

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