1LBG: Lactose operon repressor

Lactose operon repressor bound to 21-base pair symmetric operator DNA, alpha carbons only. Determined by X-ray diffraction at 4.8 Å resolution. Released 17 Feb 1996.

Method: X-ray diffraction
Resolution: 4.8 Å
Organism: Escherichia coli
Chains: 8
Atoms: 3,144
Mol. weight: 180.48 kDa
Released: 17 Feb 1996

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

Secondary structure: helices and β-sheets

1LBG contains 56 α-helices and 48 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.

Chains A, B, C and D: 14 helices, 12 β-strands

Element	Residues	Length	Sheet
α-helix	6-12	7
α-helix	17-25	9
α-helix	32-45	14
α-helix	50-58	9
β-strand	63-68	6	1
α-helix	74-90	17
β-strand	92-98	7	1
α-helix	104-116	13
β-strand	121-124	4	1
α-helix	131-137	7
β-strand	145-149	5	1
β-strand	158-161	4	1
α-helix	164-175	12
β-strand	182-185	4	2
α-helix	192-205	14
β-strand	214-217	4	2
α-helix	222-233	12
β-strand	240-244	5	2
α-helix	247-259	13
β-strand	269-274	6	2
α-helix	279-281	3
β-strand	287-290	4	2
α-helix	293-309	17
β-strand	316-318	3	1
β-strand	322-324	3	2
α-helix	340-357	18

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
DNA (5'-d(gpapaptptpgptpgpapgpcpgpcptpcpapcpapaptp*t)-3')	E, F, G, H	DNA	21
Protein (lactose operon repressor)	A, B, C, D	protein	360	Escherichia coli	P03023 (AlphaFold model)

Sequence of entity 1 (E, F, G, H), FASTA

>1LBG_1 DNA (5'-D(*GP*AP*AP*TP*TP*GP*TP*GP*AP*GP*CP*GP*CP*TP*CP*AP*CP*AP*AP*TP*T)-3') (chains E, F, G, H)
GAATTGTGAGCGCTCACAATT

Sequence of entity 2 (A, B, C, D), FASTA

>1LBG_2 PROTEIN (LACTOSE OPERON REPRESSOR) (chains A, B, C, D)
MKPVTLYDVAEYAGVSYQTVSRVVNQASHVSAKTREKVEAAMAELNYIPNRVAQQLAGKQ
SLLIGVATSSLALHAPSQIVAAIKSRADQLGASVVVSMVERSGVEACKTAVHNLLAQRVS
GLIINYPLDDQDAIAVEAACTNVPALFLDVSDQTPINSIIFSHEDGTRLGVEHLVALGHQ
QIALLAGPLSSVSARLRLAGWHKYLTRNQIQPIAEREGDWSAMSGFQQTMQMLNEGIVPT
AMLVANDQMALGAMRAITESGLRVGADISVVGYDDTEDSSCYIPPLTTIKQDFRLLGQTS
VDRLLQLSQGQAVKGNQLLPVSLVKRKTTLAPNTQTASPRALADSLMQLARQVSRLESGQ

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
1LBH 3.2 Å, Intact lactose operon repressor with gratuitous inducer iptg
2PAF 3.5 Å, Crystal Structure of the Lactose Repressor bound to anti-inducer ONPF in induced state

Browse structure collections

About this viewer

MolViewer shows 1LBG 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.