1ukl

Crystal structure of Importin-beta and SREBP-2 complex

Method: X-RAY DIFFRACTION

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

Importin beta-1 subunit

Mus musculus

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 3	Sterol regulatory element binding protein-2 × 2 （Q12772）	Consistent with protein count
2	Protein heterocomplex	Heteromer	Protein 3	Sterol regulatory element binding protein-2 × 2 （Q12772）	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	IMB1_MOUSE
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–876； UniProt 1–876 Author chain B； PDBConstruct 1–876； UniProt 1–876

Sterol regulatory element binding protein-2

Homo sapiens

UniProt Q12772

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 3	Importin beta-1 subunit × 1 （P70168）	Consistent with protein count
2	Protein heterocomplex	Heteromer	Protein 3	Importin beta-1 subunit × 1 （P70168）	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	SRBP2_HUMAN
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain C； PDBConstruct 1–61； UniProt 343–403 Author chain D； PDBConstruct 1–61； UniProt 343–403 Author chain E； PDBConstruct 1–61； UniProt 343–403 Author chain F； PDBConstruct 1–61； UniProt 343–403

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	1ukl
Deposition date deposition_date	2003-08-26
Structure title title	Crystal structure of Importin-beta and SREBP-2 complex
Keywords keywords	;Transcription factor, Nuclear transport factor, HEAT repeat, Helix-Loop-Helix Leucine zipper, PROTEIN TRANSPORT-DNA BINDING PROTEIN COMPLEX ;; PROTEIN TRANSPORT/DNA BINDING PROTEIN
Experimental Method method	X-RAY DIFFRACTION

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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.

1ukl__assembly_1__model_1

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

Download this curve (.dat)

1ukl__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1ukl__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	34.42 Å
Rg (electron density)	33.86 Å
Total Rg	34.34 Å
Atom count	7803
Residues	992
Excluded volume	139700 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1ukl__assembly_1__model_1`	trimeric （3）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`1ukl__assembly_2__model_1`	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 (2)

Entity 1 Entity 1 polymer

Description description	Importin beta-1 subunit
Molecular weight formula_weight	97271.8 kDa
Source method src_method	man
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B
Atom count atom_count	15606

MELITILEKTVSPDRLELEAAQKFLERAAVENLPTFLVELSRVLANPGNSQVARVAAGLQIKNSLTSKDPDIKAQYQQRWLAIDANARREVKNYVLQTLGTETYRPSSASQCVAGIACAEIPVSQWPELIPQLVANVTNPNSTEHMKESTLEAIGYICQDIDPEQLQDKSNEILTAIIQGMRKEEPSNNVKLAATNALLNSLEFTKANFDKESERHFIMQVVCEATQCPDTRVRVAALQNLVKIMSLYYQYMETYMGPALFAITIEAMKSDIDEVALQGIEFWSNVCDEEMDLAIEASEAAEQGRPPEHTSKFYAKGALQYLVPILTQTLTKQDENDDDDDWNPCKAAGVCLMLLSTCCEDDIVPHVLPFIKEHIKNPDWRYRDAAVMAFGSILEGPEPNQLKPLVIQAMPTLIELMKDPSVVVRDTTAWTVGRICELLPEAAINDVYLAPLLQCLIEGLSAEPRVASNVCWAFSSLAEAAYEAADVADDQEEPATYCLSSSFELIVQKLLETTDRPDGHQNNLRSSAYESLMEIVKNSAKDCYPAVQKTTLVIMERLQQVLQMESHIQSTSDRIQFNDLQSLLCATLQNVLRKVQHQDALQISDVVMASLLRMFQSTAGSGGVQEDALMAVSTLVEVLGGEFLKYMEAFKPFLGIGLKNYAEYQVCLAAVGLVGDLCRALQSNILPFCDEVMQLLLENLGNENVHRSVKPQILSVFGDIALAIGGEFKKYLEVVLNTLQQASQAQVDKSDFDMVDYLNELRESCLEAYTGIVQGLKGDQENVHPDVMLVQPRVEFILSFIDHIAGDEDHTDGVVACAAGLIGDLCTAFGKDVLKLVEARPMIHELLTEGRRSKTNKAKTLATWATKELRKLKNQA

Source Source

Source organism organism	Mus musculus
Common name common_name	house mouse
NCBI taxonomy ID ncbi_taxonomy_id	10090
Host organism host_organism	Escherichia coli BL21

Entity 2 Entity 2 polymer

Description description	Sterol regulatory element binding protein-2
Molecular weight formula_weight	7277.2 kDa
Source method src_method	man
Copy count entity_count	4

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	C,D,E,F

RSSINDKIIELKDLVMGTDAKMHKSGVLRKAIDYIKYLQQVNHKLRQENMVLKLANQKNKL

Source Source

Source organism organism	Homo sapiens
Common name common_name	human
NCBI taxonomy ID ncbi_taxonomy_id	9606
Host organism host_organism	Escherichia coli BL21

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6. Fold Classification (SCOP + CATH) 12 domains

SCOP 2.08 (6 domains)

Domain ID domain_id	d1ukla_
Class class	a — All alpha proteins
Fold Fold fold	a.118 — alpha-alpha superhelix
Superfamily Superfamily superfamily	a.118.1 — ARM repeat
Family Family family	a.118.1.1 — Armadillo repeat

Domain ID domain_id	d1uklb_
Class class	a — All alpha proteins
Fold Fold fold	a.118 — alpha-alpha superhelix
Superfamily Superfamily superfamily	a.118.1 — ARM repeat
Family Family family	a.118.1.1 — Armadillo repeat

Domain ID domain_id	d1uklc_
Class class	a — All alpha proteins
Fold Fold fold	a.38 — HLH-like
Superfamily Superfamily superfamily	a.38.1 — HLH, helix-loop-helix DNA-binding domain
Family Family family	a.38.1.1 — HLH, helix-loop-helix DNA-binding domain

Domain ID domain_id	d1ukld_
Class class	a — All alpha proteins
Fold Fold fold	a.38 — HLH-like
Superfamily Superfamily superfamily	a.38.1 — HLH, helix-loop-helix DNA-binding domain
Family Family family	a.38.1.1 — HLH, helix-loop-helix DNA-binding domain

Domain ID domain_id	d1ukle_
Class class	a — All alpha proteins
Fold Fold fold	a.38 — HLH-like
Superfamily Superfamily superfamily	a.38.1 — HLH, helix-loop-helix DNA-binding domain
Family Family family	a.38.1.1 — HLH, helix-loop-helix DNA-binding domain

Domain ID domain_id	d1uklf_
Class class	a — All alpha proteins
Fold Fold fold	a.38 — HLH-like
Superfamily Superfamily superfamily	a.38.1 — HLH, helix-loop-helix DNA-binding domain
Family Family family	a.38.1.1 — HLH, helix-loop-helix DNA-binding domain

CATH v4.4 (6 domains)

Domain ID domain_id	1uklA00
Class class	1 — Mainly Alpha
Architecture architecture	25 — Alpha Horseshoe
Topology topology	10 — Leucine-rich Repeat Variant
Homologous superfamily homologous superfamily	10 — Leucine-rich Repeat Variant

Domain ID domain_id	1uklB00
Class class	1 — Mainly Alpha
Architecture architecture	25 — Alpha Horseshoe
Topology topology	10 — Leucine-rich Repeat Variant
Homologous superfamily homologous superfamily	10 — Leucine-rich Repeat Variant

Domain ID domain_id	1uklC00
Class class	4 — Few Secondary Structures
Architecture architecture	10 — Irregular
Topology topology	280 — MYOD Basic-Helix-Loop-Helix Domain, subunit B
Homologous superfamily homologous superfamily	10 — Helix-loop-helix DNA-binding domain

Domain ID domain_id	1uklD00
Class class	4 — Few Secondary Structures
Architecture architecture	10 — Irregular
Topology topology	280 — MYOD Basic-Helix-Loop-Helix Domain, subunit B
Homologous superfamily homologous superfamily	10 — Helix-loop-helix DNA-binding domain

Domain ID domain_id	1uklE00
Class class	4 — Few Secondary Structures
Architecture architecture	10 — Irregular
Topology topology	280 — MYOD Basic-Helix-Loop-Helix Domain, subunit B
Homologous superfamily homologous superfamily	10 — Helix-loop-helix DNA-binding domain

Domain ID domain_id	1uklF00
Class class	4 — Few Secondary Structures
Architecture architecture	10 — Irregular
Topology topology	280 — MYOD Basic-Helix-Loop-Helix Domain, subunit B
Homologous superfamily homologous superfamily	10 — Helix-loop-helix DNA-binding domain

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Unit-cell length a length_a	101.092 Å
Unit-cell length b length_b	113.285 Å
Unit-cell length c length_c	240.044 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	16

Space group space_group	P 21 21 21
Space-group number int_tables_number	19
Crystal system crystal_system	—

Resolution resolution	3.000 Å
Low-resolution limit resolution_low	19.990 Å
R factor r_factor	—
R_work r_work	0.2390
R_free r_free	0.2970

Crystal structure of Importin-beta and SREBP-2 complex

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

Importin beta-1 subunit

State in the Current Structure

Other States of the Same Protein in the Database

Sterol regulatory element binding protein-2

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

1ukl__assembly_1__model_1

1ukl__assembly_1__model_1 | I(q)

1ukl__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

5. Entities and Polymers Entities & Polymers (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

6. Fold Classification (SCOP + CATH) 12 domains

SCOP 2.08 (6 domains)

CATH v4.4 (6 domains)

7. Citations (1)

Crystal structure of Importin-beta and SREBP-2 complex

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

Importin beta-1 subunit

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

Sterol regulatory element binding protein-2

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

1ukl__assembly_1__model_1

1ukl__assembly_1__model_1 | I(q)

1ukl__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

5. Entities and Polymers Entities & Polymers (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

6. Fold Classification (SCOP + CATH) 12 domains

SCOP 2.08 (6 domains)

CATH v4.4 (6 domains)

7. Citations (1)