9TKP: 70S Initiation Complex with extended IF2 bound

70S Initiation Complex with extended IF2 bound (70S IC-I). Determined by electron microscopy at 3.0 Å resolution. Released 30 Sept 2026.

Method: Electron microscopy
Resolution: 3.0 Å
Organism: Escherichia coli
Chains: 56
Atoms: 150,207
Mol. weight: 2312.8 kDa
Ligands: GTP, MG, FME
Released: 30 Sept 2026

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

Secondary structure: helices and β-sheets

9TKP contains 255 α-helices and 354 β-strands across 51 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 AA: 12 helices, 8 β-strands

Element	Residues	Length	Sheet
α-helix	6-9	4
β-strand	15-18	4	1
α-helix	19-21	3
α-helix	24-29	6
β-strand	30-34	5	1
β-strand	37-40	4	1
α-helix	42-44	3
α-helix	46-61	16
β-strand	67-69	3	2
α-helix	78-84	7
β-strand	89-91	3	2
α-helix	103-118	16
α-helix	124-127	4
α-helix	130-147	18
α-helix	148-150	3
β-strand	160-162	3	2
α-helix	169-178	10
β-strand	182-186	5	2
β-strand	197-200	4	2
α-helix	206-224	19

Chain AB: 10 helices, 8 β-strands

Element	Residues	Length	Sheet
α-helix	3-5	3
α-helix	6-9	4
α-helix	16-17	2
β-strand	19	1	3
α-helix	29-45	17
β-strand	51-57	7	3
β-strand	63-69	7	3
α-helix	72-76	5
α-helix	81-94	14
β-strand	98-104	7	3
α-helix	108-110	3
α-helix	112-124	13
α-helix	129-143	15
β-strand	147-154	8	4
α-helix	156-158	3
β-strand	163-170	8	4
β-strand	180-190	11	4
β-strand	193-204	12	4

Chain AC: 8 helices, 7 β-strands

Element	Residues	Length	Sheet
α-helix	8-14	7
α-helix	49-64	16
α-helix	68-80	13
α-helix	85-94	10
β-strand	96	1	6
α-helix	97-104	8
α-helix	110-118	9
β-strand	122-124	3	7
β-strand	127-128	2	7
β-strand	135	1	6
β-strand	140-144	5	7
α-helix	154-161	8
β-strand	170-172	3	7
β-strand	178-181	4	7
α-helix	197-203	7

Chain AD: 5 helices, 14 β-strands

Element	Residues	Length	Sheet
β-strand	13-21	9	9
β-strand	30-39	10	9
β-strand	44-48	5	9
β-strand	51-52	2	9
α-helix	55-68	14
β-strand	71-72	2	9
β-strand	76	1	10
β-strand	79	1	10
β-strand	84-85	2	11
β-strand	88	1	12
β-strand	91	1	12
β-strand	94-96	3	11
β-strand	105	1	11
α-helix	111-117	7
β-strand	123-125	3	11
β-strand	128	1	12
α-helix	132-145	14
α-helix	149-155	7
α-helix	161-164	4

Chain AE: 3 helices, 6 β-strands

Element	Residues	Length	Sheet
β-strand	7-10	4	26
α-helix	18-29	12
α-helix	30-32	3
β-strand	36	1	27
β-strand	41-45	5	26
β-strand	57-61	5	26
β-strand	64	1	27
α-helix	68-80	13
β-strand	84-87	4	26

Chain AF: 6 helices, 2 β-strands

Element	Residues	Length	Sheet
α-helix	21-29	9
α-helix	35-53	19
α-helix	57-62	6
β-strand	72-78	7	36
β-strand	83-89	7	36
α-helix	92-106	15
α-helix	115-128	14
α-helix	132-146	15

Chain AG: 3 helices, 10 β-strands

Element	Residues	Length	Sheet
α-helix	5-19	15
β-strand	23-27	5	40
α-helix	30-42	13
β-strand	46-51	6	40
β-strand	57-61	5	40
β-strand	74-76	3	41
β-strand	79	1	42
β-strand	82	1	42
β-strand	85	1	41
β-strand	100-105	6	41
β-strand	108-111	4	41
α-helix	112-118	7
β-strand	123-128	6	41

Chain AH: 6 helices, 8 β-strands

Element	Residues	Length	Sheet
β-strand	5-7	3	45
β-strand	10	1	45
β-strand	15-22	8	45
β-strand	27-29	3	45
β-strand	32-33	2	45
α-helix	34	1
α-helix	35-39	5
β-strand	60-67	8	45
α-helix	71-84	14
α-helix	91-98	8
β-strand	99	1	46
β-strand	101	1	46
α-helix	109-113	5
α-helix	123-125	3

43 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
Small ribosomal subunit protein uS2	AA	protein	241	Escherichia coli	P0A7V0 (AlphaFold model)
Small ribosomal subunit protein uS3	AB	protein	233	Escherichia coli	P0A7V3 (AlphaFold model)
Small ribosomal subunit protein uS4	AC	protein	206	Escherichia coli	P0A7V8 (AlphaFold model)
Small ribosomal subunit protein uS5	AD	protein	167	Escherichia coli	P0A7W1 (AlphaFold model)
Small ribosomal subunit protein bS6, fully modified isoform	AE	protein	135	Escherichia coli	P02358
Small ribosomal subunit protein uS7	AF	protein	179	Escherichia coli	P02359
Small ribosomal subunit protein uS8	AG	protein	130	Escherichia coli	P0A7W7
Small ribosomal subunit protein uS9	AH	protein	130	Escherichia coli	P0A7X3
Small ribosomal subunit protein uS10	AI	protein	103	Escherichia coli	P0A7R5
Small ribosomal subunit protein uS11	AJ	protein	129	Escherichia coli	P0A7R9
Small ribosomal subunit protein uS12	AK	protein	124	Escherichia coli	P0A7S3
Small ribosomal subunit protein uS13	AL	protein	118	Escherichia coli	P0A7S9

44 more molecules are not listed.

Sequence of entity 1 (AA), FASTA

>9TKP_1 Small ribosomal subunit protein uS2 (chains AA)
MATVSMRDMLKAGVHFGHQTRYWNPKMKPFIFGARNKVHIINLEKTVPMFNEALAELNKI
ASRKGKILFVGTKRAASEAVKDAALSCDQFFVNHRWLGGMLTNWKTVRQSIKRLKDLETQ
SQDGTFDKLTKKEALMRTRELEKLENSLGGIKDMGGLPDALFVIDADHEHIAIKEANNLG
IPVFAIVDTNSDPDGVDFVIPGNDDAIRAVTLYLGAVAATVREGRSQDLASQAEESFVEA
E

Sequence of entity 2 (AB), FASTA

>9TKP_2 Small ribosomal subunit protein uS3 (chains AB)
MGQKVHPNGIRLGIVKPWNSTWFANTKEFADNLDSDFKVRQYLTKELAKASVSRIVIERP
AKSIRVTIHTARPGIVIGKKGEDVEKLRKVVADIAGVPAQINIAEVRKPELDAKLVADSI
TSQLERRVMFRRAMKRAVQNAMRLGAKGIKVEVSGRLGGAEIARTEWYREGRVPLHTLRA
DIDYNTSEAHTTYGVIGVKVWIFKGEILGGMAAVEQPEKPAAQPKKQQRKGRK

Sequence of entity 3 (AC), FASTA

>9TKP_3 Small ribosomal subunit protein uS4 (chains AC)
MARYLGPKLKLSRREGTDLFLKSGVRAIDTKCKIEQAPGQHGARKPRLSDYGVQLREKQK
VRRIYGVLERQFRNYYKEAARLKGNTGENLLALLEGRLDNVVYRMGFGATRAEARQLVSH
KAIMVNGRVVNIASYQVSPNDVVSIREKAKKQSRVKAALELAEQREKPTWLEVDAGKMEG
TFKRKPERSDLSADINEHLIVELYSK

Sequence of entity 4 (AD), FASTA

>9TKP_4 Small ribosomal subunit protein uS5 (chains AD)
MAHIEKQAGELQEKLIAVNRVSKTVKGGRIFSFTALTVVGDGNGRVGFGYGKAREVPAAI
QKAMEKARRNMINVALNNGTLQHPVKGVHTGSRVFMQPASEGTGIIAGGAMRAVLEVAGV
HNVLAKAYGSTNPINVVRATIDGLENMNSPEMVAAKRGKSVEEILGK

Sequence of entity 5 (AE), FASTA

>9TKP_5 Small ribosomal subunit protein bS6, fully modified isoform (chains AE)
MRHYEIVFMVHPDQSEQVPGMIERYTAAITGAEGKIHRLEDWGRRQLAYPINKLHKAHYV
LMNVEAPQEVIDELETTFRFNDAVIRSMVMRTKHAVTEASPMVKAKDERRERRDDFANET
ADDAEAGDSEEEEEE

Sequence of entity 6 (AF), FASTA

>9TKP_6 Small ribosomal subunit protein uS7 (chains AF)
MPRRRVIGQRKILPDPKFGSELLAKFVNILMVDGKKSTAESIVYSALETLAQRSGKSELE
AFEVALENVRPTVEVKSRRVGGSTYQVPVEVRPVRRNALAMRWIVEAARKRGDKSMALRL
ANELSDAAENKGTAVKKREDVHRMAEANKAFAHYRWLSLRSFSHQAGASSKQPALGYLN

Sequence of entity 7 (AG), FASTA

>9TKP_7 Small ribosomal subunit protein uS8 (chains AG)
MSMQDPIADMLTRIRNGQAANKAAVTMPSSKLKVAIANVLKEEGFIEDFKVEGDTKPELE
LTLKYFQGKAVVESIQRVSRPGLRIYKRKDELPKVMAGLGIAVVSTSKGVMTDRAARQAG
LGGEIICYVA

Sequence of entity 8 (AH), FASTA

>9TKP_8 Small ribosomal subunit protein uS9 (chains AH)
MAENQYYGTGRRKSSAARVFIKPGNGKIVINQRSLEQYFGRETARMVVRQPLELVDMVEK
LDLYITVKGGGISGQAGAIRHGITRALMEYDESLRSELRKAGFVTRDARQVERKKVGLRK
ARRRPQFSKR

Sequence of entity 9 (AI), FASTA

>9TKP_9 Small ribosomal subunit protein uS10 (chains AI)
MQNQRIRIRLKAFDHRLIDQATAEIVETAKRTGAQVRGPIPLPTRKERFTVLISPHVNKD
ARDQYEIRTHLRLVDIVEPTEKTVDALMRLDLAAGVDVQISLG

Sequence of entity 10 (AJ), FASTA

>9TKP_10 Small ribosomal subunit protein uS11 (chains AJ)
MAKAPIRARKRVRKQVSDGVAHIHASFNNTIVTITDRQGNALGWATAGGSGFRGSRKSTP
FAAQVAAERCADAVKEYGIKNLEVMVKGPGPGRESTIRALNAAGFRITNITDVTPIPHNG
CRPPKKRRV

Sequence of entity 11 (AK), FASTA

>9TKP_11 Small ribosomal subunit protein uS12 (chains AK)
MATVNQLVRKPRARKVAKSNVPALEACPQKRGVCTRVYTTTPKKPNSALRKVCRVRLTNG
FEVTSYIGGEGHNLQEHSVILIRGGRVKDLPGVRYHTVRGALDCSGVKDRKQARSKYGVK
RPKA

Sequence of entity 12 (AL), FASTA

>9TKP_12 Small ribosomal subunit protein uS13 (chains AL)
MARIAGINIPDHKHAVIALTSIYGVGKTRSKAILAAAGIAEDVKISELSEGQIDTLRDEV
AKFVVEGDLRREISMSIKRLMDLGCYRGLRHRRGLPVRGQRTKTNARTRKGPRKPIKK

Ligands and cofactors

ID	Name	Formula	Copies
GTP	Guanosine-5'-triphosphate	C10 H16 N5 O14 P3	1
MG	Magnesium ion	Mg	1
FME	N-formylmethionine	C6 H11 N O3 S	1

Primary citation

Time-resolved visualization of IF1- and IF2-driven translation initiation in bacteria. Guerra, G.S., Zafar, H., Ge, X. et al. To be published.

Other PDB entries of the same protein (UniProt P0A7V0 (AlphaFold model), which also has an AlphaFold model), best resolution first:

8B0X 1.55 Å, Translating 70S ribosome in the unrotated state (P and E, tRNAs)
9Q87 1.55 Å, Principles of ion binding to RNA inferred from the analysis of a 1.55 Angstrom…
4ODN 1.6 Å, Structure of SlyD from Thermus thermophilus in complex with S2-plus peptide
7OXH 1.7 Å, ttSlyD with pseudo-wild-type S2 peptide
4ODP 1.75 Å, Structure of SlyD delta-IF from Thermus thermophilus in complex with S2-W23A peptide
4ODM 1.75 Å, Structure of SlyD from Thermus thermophilus in complex with S2-W23A peptide
8CGJ 1.79 Å, Streptomycin bound to the 30S body
8CF1 1.82 Å, Tetracycline bound to the 30S head
7OXJ 1.85 Å, ttSlyD with M8A pseudo-wild-type S2 peptide
8FTO 1.85 Å, E. coli 70S ribosome with an improved MS2 tag inserted in H98
9GHE 1.87 Å, Staphylococcus aureus FusB bound to the small subunit of the Escherichia coli 70S…
9T0Y 1.87 Å, E. coli 70S ribosome from delta-9 strain

Browse structure collections

About this viewer

MolViewer shows 9TKP directly in your browser with nothing to install. Switch between cartoon, ball-and-stick, spacefill and surface views, color by chain, secondary structure or B-factor, measure distances, angles and dihedrals, and share or embed the view.