SAXSdb — 1lcd

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1. Protein Identity and Related Structures Protein Identity & Related Structures

Lac Repressor

Escherichia coli

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein–DNA	Monomer	Protein 1 DNA 2	;DNA (5'-D(APAPTPTPGPTPGPAPGPCPG)-3') ; × 1 ;DNA (5'-D(CPGPCPTPCPAPCPAPAPTPT)-3') ; × 1 SODIUM ION × 1 water × 3	Consistent with all polymers

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	LACI_ECOLI
Isoform	—
PDB entities	3
Chains and sequence ranges	Author chain A； PDBConstruct 1–51； UniProt 1–51

The page prioritizes protein identity, the current assembly, associated components, oligomeric state and cross-PDB links. Chain mapping and sequence ranges are retained as data evidence. Internal IDs, import timestamps and assembly operation expressions are maintenance fields and are not shown here.

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2. Structure Basics 2. Structure Basics

Entry ID entry_id	1lcd
Deposition date deposition_date	1993-03-25
Structure title title	STRUCTURE OF THE COMPLEX OF LAC REPRESSOR HEADPIECE AND AN 11 BASE-PAIR HALF-OPERATOR DETERMINED BY NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY AND RESTRAINED MOLECULAR DYNAMICS
Keywords keywords	GENE REGULATION/DNA, GENE REGULATION-DNA complex; GENE REGULATION/DNA
Experimental Method method	SOLUTION NMR

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3. Official assembly/model SAXS Official SAXS Profiles

This page reads only the latest assembly calculations. Every curve maps to an explicit PDB entry, official biological assembly and coordinate model.

1lcd__assembly_1__model_2

Assembly 1 · Model 2 · CRYSOL 4.1.3-1-20251215 (887e7ef)

Download this curve (.dat)

1lcd__assembly_1__model_2 | I(q)

100 plotted points; both axes use logarithmic scales.

1lcd__assembly_1__model_2 | P(r) · Pending

P(r) will be calculated and displayed separately for the same assembly/model.

Rg（Guinier）	14.95 Å
Rg (electron density)	14.16 Å
Total Rg	15.21 Å
Atom count	990
Residues	73
Excluded volume	13661 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1lcd__assembly_1__model_1`	trimeric （3）	Success	4.1.3-1-20251215 (887e7ef)	View Download
1	2	`1lcd__assembly_1__model_2`	trimeric （3）	Success	4.1.3-1-20251215 (887e7ef)	View Download
1	3	`1lcd__assembly_1__model_3`	trimeric （3）	Success	4.1.3-1-20251215 (887e7ef)	View Download

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4. Crystallography and Experiment 4. Crystallography & Experiment

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5. Entities and Polymers Entities & Polymers (5)

Entity 1 Entity 1 polymer

Description description	;DNA (5'-D(APAPTPTPGPTPGPAPGPCP*G)-3') ;
Molecular weight formula_weight	3413.2 kDa
Source method src_method	syn
Copy count entity_count	1

Polymer Polymer

Polymer type type	polydeoxyribonucleotide
Chain IDs strand_id	B
Atom count atom_count	3384

AATTGTGAGCG

Entity 2 Entity 2 polymer

Description description	;DNA (5'-D(CPGPCPTPCPAPCPAPAPTP*T)-3') ;
Molecular weight formula_weight	3293.2 kDa
Source method src_method	syn
Copy count entity_count	1

Polymer Polymer

Polymer type type	polydeoxyribonucleotide
Chain IDs strand_id	C

CGCTCACAATT

Entity 3 Entity 3 polymer

Description description	Lac Repressor
Molecular weight formula_weight	5693.4 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A

MKPVTLYDVAEYAGVSYQTVSRVVNQASHVSAKTREKVEAAMAELNYIPNR

Source Source

Source organism organism	Escherichia coli
NCBI taxonomy ID ncbi_taxonomy_id	562

Entity 4 Entity 4 non-polymer

Description description	SODIUM ION
Molecular weight formula_weight	23.0 kDa
Source method src_method	syn
Copy count entity_count	1

Entity 5 Entity 5 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	49

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6. Fold Classification (SCOP + CATH) 2 domains

SCOP 2.08 (1 domains)

Domain ID domain_id	d1lcda_
Class class	a — All alpha proteins
Fold Fold fold	a.35 — lambda repressor-like DNA-binding domains
Superfamily Superfamily superfamily	a.35.1 — lambda repressor-like DNA-binding domains
Family Family family	a.35.1.5 — GalR/LacI-like bacterial regulator

CATH v4.4 (1 domains)

Domain ID domain_id	1lcdA00
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	260 — 434 Repressor (Amino-terminal Domain)
Homologous superfamily homologous superfamily	40 — lambda repressor-like DNA-binding domains

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7. Citations (10)

;Structure of the complex of lac repressor headpiece and an 11 base-pair half-operator determined by nuclear magnetic resonance spectroscopy and restrained molecular dynamics. ;

J.Mol.Biol. (1993)

PMID: 8230225 · DOI: 10.1006/jmbi.1993.1598 PRIMARY

;Assignment of the 1H-NMR Spectrum of a Lac Repressor Headpiece-Operator Complex in H2O and Identification of Noes. Consequences for Protein-DNA Interaction ;

Eur.J.Biochem. (1990)

Two-Dimensional NMR Study of a Protein-DNA Complex. Lac Repressor Headpiece-Operator Interaction

Biochem.Pharm. (1990)

1H NMR Study of a Complex between the Lac Repressor Headpiece and a 22 Base Pair Symmetric Lac Operator

Biochemistry (1989)

NMR Based Docking Studies of Lac Repressor Headpiece on a Lac Operator Fragment

Ucla Symp.Mol.Cell.Biol., New Ser. (1989)

The Interaction of Lac Repressor Headpiece with its Operator: An NMR View

Protein Seq.Data Anal. (1988)

;Combined Procedure of Distance Geometry and Restrained Molecular Dynamics Techniques for Protein Structure Determination from Nuclear Magnetic Resonance Data: Application to the DNA Binding Domain of Lac Repressor from Escherichia Coli ;

Proteins (1988)

A Two-Dimensional NMR Study of the Complex of Lac Repressor Headpiece with a 14 Base Pair Lac Operator Fragment

Nato Asi Ser.,Ser.A (1987)

Complex of Lac Repressor Headpiece with a 14 Base Pair Lac Operator Fragment Studied by Two-Dimensional Nuclear Magnetic Resonance

J.Mol.Biol. (1987)

;Restrained Molecular Dynamics Procedure for Protein Tertiary Structure Determination from NMR Data: A Lac Repressor Headpiece Structure Based on Information on J-Coupling and from Presence and Absence of Noes ;

Isr.J.Chem. (1986)

Unit-cell length a length_a	1.000 Å
Unit-cell length b length_b	1.000 Å
Unit-cell length c length_c	1.000 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	90.00 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	1

Space group space_group	P 1
Space-group number int_tables_number	1
Crystal system crystal_system	—

STRUCTURE OF THE COMPLEX OF LAC REPRESSOR HEADPIECE AND AN 11 BASE-PAIR HALF-OPERATOR DETERMINED BY NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY AND RESTRAINED MOLECULAR DYNAMICS

1. Protein Identity and Related Structures Protein Identity & Related Structures

Lac Repressor

State in the Current Structure

Other States of the Same Protein in the Database

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

1lcd__assembly_1__model_2

1lcd__assembly_1__model_2 | I(q)

1lcd__assembly_1__model_2 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

5. Entities and Polymers Entities & Polymers (5)

Entity 1 Entity 1 polymer

Polymer Polymer

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 polymer

Polymer Polymer

Source Source

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 water

6. Fold Classification (SCOP + CATH) 2 domains

SCOP 2.08 (1 domains)

CATH v4.4 (1 domains)

7. Citations (10)

STRUCTURE OF THE COMPLEX OF LAC REPRESSOR HEADPIECE AND AN 11 BASE-PAIR HALF-OPERATOR DETERMINED BY NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY AND RESTRAINED MOLECULAR DYNAMICS

1. Protein Identity and Related Structures Protein Identity & Related Structures

Lac Repressor

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

1lcd__assembly_1__model_2

1lcd__assembly_1__model_2 | I(q)

1lcd__assembly_1__model_2 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

5. Entities and Polymers Entities & Polymers (5)

Entity 1 Entity 1 polymer

Polymer Polymer

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 polymer

Polymer Polymer

Source Source

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 water

6. Fold Classification (SCOP + CATH) 2 domains

SCOP 2.08 (1 domains)

CATH v4.4 (1 domains)

7. Citations (10)