9BCR: PDB entry 9BCR

Cryo-EM structure of a bacterial prototype ATP-binding cassette transporter MalFGK2. Determined by electron microscopy at 3.26 Å resolution. Released 30 Apr 2025.

Method: Electron microscopy
Resolution: 3.26 Å
Organism: Escherichia coli K-12
Chains: 4
Atoms: 10,595
Mol. weight: 170.82 kDa
Released: 30 Apr 2025

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

Secondary structure: helices and β-sheets

9BCR contains 66 α-helices and 57 β-strands across 4 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 C: 12 helices, 26 β-strands

Element	Residues	Length	Sheet
β-strand	7-8	2	4
β-strand	9-13	5	5
β-strand	16-22	7	5
β-strand	31-35	5	6
α-helix	39-50	12
β-strand	57-59	3	4
β-strand	61-62	2	7
β-strand	65-66	2	7
α-helix	72-75	4
β-strand	77-80	4	6
α-helix	92-103	12
α-helix	107-120	14
α-helix	124-126	3
α-helix	131-133	3
α-helix	136-150	15
β-strand	154-157	4	6
α-helix	166-183	18
β-strand	186-191	6	6
α-helix	194-199	6
β-strand	203-207	5	6
β-strand	212-216	5	6
α-helix	218-223	6
β-strand	227	1	8
α-helix	228-233	6
α-helix	238-239	2
β-strand	240-249	10	9
β-strand	253-257	5	9
β-strand	265-269	5	9
β-strand	280-285	6	9
β-strand	291-292	2	10
β-strand	299-306	8	10
β-strand	309	1	10
β-strand	313-319	7	10
β-strand	326-332	7	10
β-strand	342-346	5	10
β-strand	352-355	4	9
β-strand	360	1	8
β-strand	361	1	9

Chain D: 14 helices, 25 β-strands

Element	Residues	Length	Sheet
β-strand	4-13	10	11
β-strand	16-25	10	11
β-strand	31-35	5	12
α-helix	41-50	10
β-strand	57-62	6	11
β-strand	65-66	2	11
α-helix	72-75	4
β-strand	77-80	4	12
α-helix	92-103	12
α-helix	107-120	14
α-helix	136-150	15
β-strand	154-158	5	12
α-helix	166-183	18
β-strand	186-190	5	12
α-helix	194-200	7
β-strand	203-208	6	12
β-strand	211-216	6	12
α-helix	218-223	6
β-strand	227	1	13
α-helix	228-233	6
α-helix	238-239	2
β-strand	240-249	10	14
β-strand	253-257	5	14
β-strand	265-269	5	14
β-strand	270	1	15
β-strand	280-285	6	14
α-helix	290	1
β-strand	291-292	2	16
α-helix	293-295	3
β-strand	299-309	11	16
β-strand	313-319	7	16
α-helix	326	1
β-strand	327-332	6	16
β-strand	342-346	5	16
β-strand	353-355	3	14
β-strand	360	1	13
β-strand	361-362	2	14
α-helix	363	1
β-strand	364	1	15

Chain H: 22 helices, 4 β-strands

Element	Residues	Length	Sheet
α-helix	38-49	12
α-helix	54-58	5
α-helix	64-75	12
α-helix	76-80	5
α-helix	81-90	10
β-strand	92	1	1
α-helix	252-254	3
β-strand	258	1	1
α-helix	262-269	8
α-helix	274-306	33
α-helix	314-326	13
α-helix	329-339	11
α-helix	347-354	8
α-helix	365-394	30
α-helix	398-406	9
α-helix	410-413	4
α-helix	414-418	5
α-helix	419-438	20
α-helix	441-447	7
β-strand	453	1	2
α-helix	454	1
β-strand	462	1	2
α-helix	467-476	10
α-helix	478-480	3
α-helix	484-488	5
α-helix	490-509	20

Chain I: 18 helices, 2 β-strands

Element	Residues	Length	Sheet
α-helix	8-39	32
α-helix	57-63	7
α-helix	81-111	31
α-helix	118-129	12
α-helix	137-148	12
α-helix	152-154	3
α-helix	159-166	8
α-helix	167-169	3
α-helix	170-183	14
α-helix	187-195	9
α-helix	199-202	4
α-helix	203-207	5
α-helix	208-210	3
α-helix	212-227	16
α-helix	231-235	5
β-strand	253	1	3
β-strand	258	1	3
α-helix	260-269	10
α-helix	272-276	5
α-helix	277-281	5

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Maltose/maltodextrin transport system permease protein MalF	H	protein	514	Escherichia coli K-12	P02916 (AlphaFold model)
Maltose/maltodextrin transport system permease protein MalG	I	protein	286	Escherichia coli K-12	P68183 (AlphaFold model)
Maltose/maltodextrin import ATP-binding protein MalK	C	protein	371	Escherichia coli K-12	P68187 (AlphaFold model)
Maltose/maltodextrin import ATP-binding protein MalK	D	protein	373	Escherichia coli K-12	P68187 (AlphaFold model)

Sequence of entity 1 (H), FASTA

>9BCR_1 Maltose/maltodextrin transport system permease protein MalF (chains H)
MDVIKKKHWWQSDALKWSVLGLLGLLVGYLVVLMYAQGEYLFAITTLILSSAGLYIFANR
KAYAWRYVYPGMAGMGLFVLFPLVCTIAIAFTNYSSTNQLTFERAQEVLLDRSWQAGKTY
NFGLYPAGDEWQLALSDGETGKNYLSDAFKFGGEQKLQLKETTAQPEGERANLRVITQNR
QALSDITAILPDGNKVMMSSLRQFSGTQPLYTLDGDGTLTNNQSGVKYRPNNQIGFYQSI
TADGNWGDEKLSPGYTVTTGWKNFTRVFTDEGIQKPFLAIFVWTVVFSLITVFLTVAVGM
VLACLVQWEALRGKAVYRVLLILPYAVPSFISILIFKGLFNQSFGEINMMLSALFGVKPA
WFSDPTTARTMLIIVNTWLGYPYMMILCMGLLKAIPDDLYEASAMDGAGPFQNFFKITLP
LLIKPLTPLMIASFAFNFNNFVLIQLLTNGGPDRLGTTTPAGYTDLLVNYTYRIAFEGGG
GQDFGLAAAIATLIFLLVGALAIVNLKATRMKFD

Sequence of entity 2 (I), FASTA

>9BCR_2 Maltose/maltodextrin transport system permease protein MalG (chains I)
AMVQPKSQKARLFITHLLLLLFIAAIMFPLLMVVAISLRQGNFATGSLWPEQISWDHWKL
ALGFSVEQADGRIWPPPFPVLLWLWNSVKVAGISAIGIVALSTTCAYAFARMRFPGKATL
LKGMLIFQMFPAVLSLVALYALFDRLGEYIPFIGLNTHGGVIFAYLGGIALHVWTIKGYF
ETIDSSLEEAAALDGATPWQAFRLVLLPLSVPILAVVFILSFIAAITEVPVASLLLRDVN
SYTLAVGMQQYLNPQNYLWGDFAAAAVMSALPITIVFLLAQRWLVN

Sequence of entity 3 (C), FASTA

>9BCR_3 Maltose/maltodextrin import ATP-binding protein MalK (chains C)
ASVQLQNVTKAWGEVVVSKDINLDIHEGEFVVFVGPSGCGKSTLLRMIAGLETITSGDLF
IGEKRMNDTPPAERGVGMVFQSYALYPHLSVAENMSFGLKLAGAKKEVINQRVNQVAEVL
QLAHLLDRKPKALSGGQRQRVAIGRTLVAEPSVFLLDEPLSNLDAALRVQMRIEISRLHK
RLGRTMIYVTHDQVEAMTLADKIVVLDAGRVAQVGKPLELYHYPADRFVAGFIGSPKMNF
LPVKVTATAIDQVQVELPMPNRQQVWLPVESRDVQVGANMSLGIRPEHLLPSDIADVILE
GEVQVVEQLGNETQIHIQIPSIRQNLVYRQNDVVLVEEGATFAIGLPPERCHLFREDGTA
CRRLHKEPGVA

Sequence of entity 4 (D), FASTA

>9BCR_4 Maltose/maltodextrin import ATP-binding protein MalK (chains D)
ASVQLQNVTKAWGEVVVSKDINLDIHEGEFVVFVGPSGCGKSTLLRMIAGLETITSGDLF
IGEKRMNDTPPAERGVGMVFQSYALYPHLSVAENMSFGLKLAGAKKEVINQRVNQVAEVL
QLAHLLDRKPKALSGGQRQRVAIGRTLVAEPSVFLLDEPLSNLDAALRVQMRIEISRLHK
RLGRTMIYVTHDQVEAMTLADKIVVLDAGRVAQVGKPLELYHYPADRFVAGFIGSPKMNF
LPVKVTATAIDQVQVELPMPNRQQVWLPVESRDVQVGANMSLGIRPEHLLPSDIADVILE
GEVQVVEQLGNETQIHIQIPSIRQNLVYRQNDVVLVEEGATFAIGLPPERCHLFREDGTA
CRRLHKEPGVAHH

Primary citation

DeFrND: detergent-free reconstitution into native nanodiscs with designer membrane scaffold peptides. Ren, Q., Wang, J., Idikuda, V. et al. Nat Commun (2025) 16:7973-7973. DOI 10.1038/s41467-025-63275-8 · PubMed

Other PDB entries of the same protein (UniProt P02916 (AlphaFold model), which also has an AlphaFold model), best resolution first:

3RLF 2.2 Å, Crystal structure of the maltose-binding protein/maltose transporter complex in an…
3PUW 2.3 Å, Crystal Structure of an outward-facing MBP-Maltose transporter complex bound to ADP-AlF4
3PUX 2.3 Å, Crystal Structure of an outward-facing MBP-Maltose transporter complex bound to ADP-BeF3
4KI0 2.38 Å, Crystal structure of the maltose-binding protein/maltose transporter complex in an…
3PUV 2.4 Å, Crystal Structure of an outward-facing MBP-Maltose transporter complex bound to ADP-VO4
2R6G 2.8 Å, The Crystal Structure of the E. coli Maltose Transporter
3PUZ 2.9 Å, Crystal Structure of a pre-translocation state MBP-Maltose transporter complex bound to…
4KHZ 2.9 Å, Crystal structure of the maltose-binding protein/maltose transporter complex in an…
3PUY 3.1 Å, Crystal Structure of an outward-facing MBP-Maltose transporter complex bound to AMP-PNP…
3PV0 3.1 Å, Crystal Structure of a pre-translocation state MBP-Maltose transporter complex without…
9NQJ 3.34 Å, Cryo-EM structure of a bacterial prototype ATP-binding cassette transporter MalFGK2.
4JBW 3.91 Å, Crystal structure of E. coli maltose transporter MalFGK2 in complex with its regulatory…

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