1KTK: Exotoxin type C

Complex of Streptococcal pyrogenic enterotoxin C (SpeC) with a human T cell receptor beta chain (Vbeta2.1). Determined by X-ray diffraction at 3.0 Å resolution. Released 7 Jun 2002.

Method: X-ray diffraction
Resolution: 3.0 Å
Organisms: Streptococcus pyogenes, Homo sapiens
Chains: 6
Atoms: 9,511
Mol. weight: 152.46 kDa
Released: 7 Jun 2002

Explore 1KTK in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

1KTK contains 32 α-helices and 105 β-strands across 6 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: 7 helices, 15 β-strands

Element	Residues	Length	Sheet
α-helix	7-17	11
α-helix	20-21	2
β-strand	22-32	11	1
β-strand	36-40	5	1
β-strand	50-54	5	1
β-strand	68-73	6	1
β-strand	83-86	4	1
β-strand	90-92	3	1
β-strand	100-101	2	2
α-helix	102	1
β-strand	104-108	5	3
β-strand	114	1	3
β-strand	121-122	2	2
β-strand	126-128	3	4
α-helix	129-144	16
β-strand	155-162	8	3
β-strand	168-171	4	3
α-helix	181-184	4
α-helix	185-190	6
β-strand	193-195	3	4
α-helix	196-198	3
β-strand	199-207	9	3

Chain B: 7 helices, 18 β-strands

Element	Residues	Length	Sheet
α-helix	6-13	8
β-strand	22	1	5
β-strand	27	1	6
β-strand	28-32	5	7
β-strand	36-40	5	7
β-strand	50-54	5	7
β-strand	69-70	2	6
β-strand	73	1	5
β-strand	83-86	4	7
β-strand	91-92	2	6
α-helix	93-94	2
β-strand	100-101	2	8
α-helix	102-103	2
β-strand	104-107	4	9
β-strand	115	1	9
β-strand	121-122	2	8
β-strand	126	1	10
α-helix	129-144	16
β-strand	156-162	7	9
β-strand	167-171	5	9
α-helix	181-185	5
α-helix	186-188	3
β-strand	195	1	10
α-helix	196-198	3
β-strand	199-206	8	9

Chain C: 8 helices, 19 β-strands

Element	Residues	Length	Sheet
α-helix	12-17	6
α-helix	20-21	2
β-strand	22	1	11
β-strand	27-28	2	12
β-strand	29-32	4	13
β-strand	36-40	5	13
α-helix	42-45	4
β-strand	50-54	5	13
α-helix	57-60	4
β-strand	68-71	4	12
β-strand	73	1	11
β-strand	75-77	3	13
β-strand	83-86	4	13
β-strand	90-92	3	12
α-helix	93-94	2
β-strand	100-101	2	14
β-strand	104-108	5	15
β-strand	114-115	2	15
β-strand	121-122	2	14
β-strand	126-128	3	16
α-helix	129-144	16
β-strand	157-162	6	15
β-strand	168-171	4	15
α-helix	181-184	4
α-helix	185-188	4
β-strand	193-195	3	16
β-strand	199-206	8	15

Chain D: 9 helices, 20 β-strands

Element	Residues	Length	Sheet
α-helix	9-16	8
α-helix	20-21	2
β-strand	22	1	17
β-strand	27	1	18
β-strand	29-32	4	19
β-strand	37-40	4	19
β-strand	50-53	4	19
α-helix	57-60	4
β-strand	69-71	3	18
β-strand	73	1	17
β-strand	75	1	19
β-strand	83-86	4	19
β-strand	90-92	3	18
α-helix	93-94	2
β-strand	100-101	2	20
α-helix	102	1
β-strand	103-108	6	21
β-strand	109	1	22
β-strand	111	1	22
β-strand	121-122	2	20
β-strand	126-128	3	23
α-helix	129-139	11
β-strand	155-161	7	21
β-strand	168-171	4	21
α-helix	181-184	4
α-helix	185-188	4
β-strand	193-195	3	23
α-helix	196-198	3
β-strand	201-207	7	21

Chain E: 1 helix, 20 β-strands

Element	Residues	Length	Sheet
β-strand	4-6	3	24
β-strand	20-25	6	24
β-strand	32-36	5	25
β-strand	44-49	6	25
β-strand	55-57	3	25
β-strand	66-71	6	24
β-strand	74-78	5	24
β-strand	89-91	3	25
β-strand	112-113	2	25
β-strand	126-130	5	26
β-strand	142-143	2	27
β-strand	146-150	5	26
β-strand	161-163	3	28
β-strand	166-167	2	28
β-strand	173-174	2	26
α-helix	178	1
β-strand	179-180	2	26
β-strand	190-195	6	26
β-strand	198-199	2	27
β-strand	209-214	6	28
β-strand	237-242	6	28

Chain F: 0 helices, 13 β-strands

Element	Residues	Length	Sheet
β-strand	5-6	2	29
β-strand	18	1	30
β-strand	22	1	31
β-strand	23-24	2	29
β-strand	33	1	32
β-strand	48	1	32
β-strand	65-69	5	31
β-strand	75-79	5	31
β-strand	80	1	30
β-strand	90	1	33
β-strand	112	1	33
β-strand	149-150	2	34
β-strand	191-192	2	34

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Exotoxin type C	A, B, C, D	protein	208	Streptococcus pyogenes	Q8NKX2 (AlphaFold model)
T-cell receptor beta chain	E, F	protein	247	Homo sapiens	P01850 (AlphaFold model)

Sequence of entity 1 (A, B, C, D), FASTA

>1KTK_1 Exotoxin type C (chains A, B, C, D)
DSKKDISNVKSDLLYAYTITPYDYKDCRVNFSTTHTLNIDTQKYRGKDYYISSEMSYEAS
QKFKRDDHVDVFGLFYILNSHTGEYIYGGITPAQNNKVNHKLLGNLFISGESQQNLNNKI
ILEKDIVTFQEIDFKIRKYLMDNYKIYDATSPYVSGRIEIGTKDGKHEQIDLFDSPNEGT
RSDIFAKYKDNRIINMKNFSHFDIYLEK

Sequence of entity 2 (E, F), FASTA

>1KTK_2 T-cell receptor beta chain (chains E, F)
GAVVSQHPSRVIAKSGTSVKIECRSLDFQATTMFWYRQFPKQSLMLMATSAEGSKATYEQ
GVEKDKFLINHASLTLSTLTVTSAHPEDSSFYICSALAGSGSSTDTQYFGPGTRLTVLED
LKNFPPEVAVFEPSEAEISHTQKATLVCLATGFYPDHVELSWWVNGKEVHSGVSTDPQPL
KEQPALNDSRYALSSRLRVSATFWQNPRNHFRCQVQFYGLSENDEWTQDRAKPVTQIVSA
EAWGRAD

Primary citation

Structures of two streptococcal superantigens bound to TCR beta chains reveal diversity in the architecture of T cell signaling complexes. Sundberg, E.J., Li, H., Llera, A.S. et al. Structure (2002) 10:687-699. DOI 10.1016/S0969-2126(02)00759-1 · PubMed

Other PDB entries of the same protein (UniProt Q8NKX2 (AlphaFold model), which also has an AlphaFold model), best resolution first:

1AN8 2.4 Å, Crystal structure of the streptococcal superantigen spe-C
1HQR 3.2 Å, Crystal structure of a superantigen bound to the high-affinity, zinc-dependent site on…

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