1LBH: PDB entry 1LBH

Intact lactose operon repressor with gratuitous inducer iptg. Determined by X-ray diffraction at 3.2 Å resolution. Released 11 Jul 1996.

Method: X-ray diffraction
Resolution: 3.2 Å
Organism: Escherichia coli
Chains: 4
Atoms: 8,932
Mol. weight: 155.58 kDa
Ligands: IPT
Released: 11 Jul 1996

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

Secondary structure: helices and β-sheets

1LBH contains 49 α-helices and 60 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 A: 13 helices, 17 β-strands

Element	Residues	Length	Sheet
β-strand	63-68	6	1
α-helix	75-89	15
β-strand	93-98	6	1
α-helix	104-114	11
β-strand	121-127	7	1
α-helix	130-139	10
β-strand	145-149	5	1
β-strand	158	1	1
β-strand	160-161	2	2
α-helix	163-176	14
β-strand	182-186	5	3
α-helix	192-207	16
β-strand	214-217	4	3
α-helix	222-234	13
β-strand	241-244	4	3
α-helix	247-259	13
β-strand	264	1	4
β-strand	268	1	4
β-strand	269-271	3	3
β-strand	274	1	5
α-helix	277-281	5
β-strand	287	1	3
β-strand	288-291	4	5
α-helix	293-308	16
β-strand	318-319	2	2
α-helix	320	1
β-strand	321-324	4	5
α-helix	325	1
α-helix	343-353	11
α-helix	354-356	3

Chain B: 11 helices, 16 β-strands

Element	Residues	Length	Sheet
β-strand	63-68	6	1
α-helix	74-90	17
β-strand	93-98	6	1
α-helix	105-116	12
β-strand	122-124	3	1
α-helix	130-139	10
β-strand	145-147	3	1
β-strand	158-161	4	1
α-helix	163-176	14
β-strand	182-186	5	6
α-helix	192-204	13
β-strand	214-217	4	6
α-helix	222-234	13
β-strand	241-244	4	6
α-helix	247-259	13
α-helix	262-263	2
β-strand	264	1	7
β-strand	268	1	7
β-strand	269-271	3	6
β-strand	274	1	8
α-helix	277-280	4
β-strand	287	1	6
β-strand	288-290	3	8
α-helix	294-308	15
β-strand	316-319	4	1
β-strand	322-324	3	8
α-helix	341-353	13

Chain C: 14 helices, 12 β-strands

Element	Residues	Length	Sheet
β-strand	64-68	5	9
α-helix	71-73	3
α-helix	75-90	16
α-helix	92-94	3
β-strand	96-98	3	9
α-helix	106-117	12
β-strand	121-124	4	9
α-helix	130-138	9
β-strand	145-147	3	9
β-strand	158-161	4	9
α-helix	163-175	13
β-strand	182-186	5	10
α-helix	192-207	16
β-strand	214-217	4	10
α-helix	222-234	13
β-strand	241-244	4	10
α-helix	247-259	13
β-strand	269-274	6	10
α-helix	277-281	5
α-helix	285-286	2
β-strand	287-291	5	10
α-helix	293-308	16
β-strand	316-319	4	9
α-helix	320	1
β-strand	321-324	4	10
α-helix	342-352	11

Chain D: 11 helices, 15 β-strands

Element	Residues	Length	Sheet
β-strand	63-68	6	9
α-helix	74-87	14
β-strand	93-98	6	9
α-helix	105-116	12
β-strand	121-125	5	9
α-helix	130-140	11
β-strand	145-147	3	9
β-strand	158	1	9
β-strand	159-161	3	11
α-helix	163-177	15
β-strand	182-186	5	12
α-helix	192-207	16
β-strand	215-217	3	12
α-helix	222-234	13
β-strand	241-244	4	12
α-helix	248-259	12
α-helix	262-263	2
β-strand	264	1	13
β-strand	268	1	13
β-strand	270-274	5	12
α-helix	277-281	5
β-strand	287-290	4	12
α-helix	293-308	16
β-strand	317-319	3	11
β-strand	322-324	3	12
α-helix	341-354	14

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Intact lactose operon repressor with gratuitous inducer iptg	A, B, C, D	protein	360	Escherichia coli	P03023 (AlphaFold model)

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

>1LBH_1 INTACT LACTOSE OPERON REPRESSOR WITH GRATUITOUS INDUCER IPTG (chains A, B, C, D)
MKPVTLYDVAEYAGVSYQTVSRVVNQASHVSAKTREKVEAAMAELNYIPNRVAQQLAGKQ
SLLIGVATSSLALHAPSQIVAAIKSRADQLGASVVVSMVERSGVEACKTAVHNLLAQRVS
GLIINYPLDDQDAIAVEAACTNVPALFLDVSDQTPINSIIFSHEDGTRLGVEHLVALGHQ
QIALLAGPLSSVSARLRLAGWHKYLTRNQIQPIAEREGDWSAMSGFQQTMQMLNEGIVPT
AMLVANDQMALGAMRAITESGLRVGADISVVGYDDTEDSSCYIPPLTTIKQDFRLLGQTS
VDRLLQLSQGQAVKGNQLLPVSLVKRKTTLAPNTQTASPRALADSLMQLARQVSRLESGQ

Ligands and cofactors

ID	Name	Formula	Copies
IPT	1-methylethyl 1-thio-beta-D-galactopyranoside	C9 H18 O5 S	4

Primary citation

Crystal structure of the lactose operon repressor and its complexes with DNA and inducer. Lewis, M., Chang, G., Horton, N.C. et al. Science (1996) 271:1247-1254. PubMed

Other PDB entries of the same protein (UniProt P03023 (AlphaFold model), which also has an AlphaFold model), best resolution first:

8GOH 1.1 Å, Homotetramic Antiparallel Coiled-Coil of 23-residues LacI C-terminal tetramerization helix
1JYE 1.7 Å, Structure of a Dimeric Lac Repressor with C-terminal Deletion and K84L Substitution
2P9H 2.0 Å, High resolution structure of the Lactose Repressor bound to IPTG
3EDC 2.1 Å, Crystal Structure of a 1.6-hexanediol Bound Tetrameric Form of Escherichia coli…
1EFA 2.6 Å, Crystal structure of the lac repressor dimer bound to operator and the anti-inducer onpf
1TLF 2.6 Å, Unprecedented quaternary structure of E. Coli lac repressor core tetramer: implications…
1LBI 2.7 Å, Lac repressor
4RZS 2.71 Å, Lac repressor engineered to bind sucralose, unliganded tetramer
1JYF 3.0 Å, Structure of the Dimeric Lac Repressor with an 11-residue C-terminal Deletion.
4RZT 3.1 Å, Lac repressor engineered to bind sucralose, sucralose-bound tetramer
2PAF 3.5 Å, Crystal Structure of the Lactose Repressor bound to anti-inducer ONPF in induced state
2PE5 3.5 Å, Crystal Structure of the Lac Repressor bound to ONPG in repressed state

Browse structure collections

About this viewer

MolViewer shows 1LBH 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.