1go4

Crystal structure of Mad1-Mad2 reveals a conserved Mad2 binding motif in Mad1 and Cdc20.

Method: X-RAY DIFFRACTION

▼

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

Mitotic spindle assembly checkpoint protein MAD2A

Homo sapiens

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 8	Mitotic spindle assembly checkpoint protein MAD1 × 4 （Q9Y6D9） water × 8	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	MD2L1_HUMAN
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–205； UniProt 1–205 Author chain B； PDBConstruct 1–205； UniProt 1–205 Author chain C； PDBConstruct 1–205； UniProt 1–205 Author chain D； PDBConstruct 1–205； UniProt 1–205

Mitotic spindle assembly checkpoint protein MAD1

Homo sapiens

UniProt Q9Y6D9

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 8	Mitotic spindle assembly checkpoint protein MAD2A × 4 （Q13257） water × 8	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	MD1L1_HUMAN
Isoform	Q9Y6D9-3
PDB entities	2
Chains and sequence ranges	Author chain E； PDBConstruct 1–100； UniProt 393–492 Author chain F； PDBConstruct 1–100； UniProt 393–492 Author chain G； PDBConstruct 1–100； UniProt 393–492 Author chain H； PDBConstruct 1–100； UniProt 393–492

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.

▼

2. Structure Basics 2. Structure Basics

Entry ID entry_id	1go4
Deposition date deposition_date	2001-10-17
Structure title title	Crystal structure of Mad1-Mad2 reveals a conserved Mad2 binding motif in Mad1 and Cdc20.
Keywords keywords	MITOTIC SPINDLE CHECKPOINT, CELL CYCLE, MITOSIS, NUCLEAR PRO; CELL CYCLE
Experimental Method method	X-RAY DIFFRACTION

▼

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.

1go4__assembly_1__model_1

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

Download this curve (.dat)

1go4__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1go4__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	46.38 Å
Rg (electron density)	46.89 Å
Total Rg	47.06 Å
Atom count	9300
Residues	1146
Excluded volume	165820 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1go4__assembly_1__model_1`	octameric （8）	Success	4.1.3-1-20251215 (887e7ef)	View Download

▶

4. Crystallography and Experiment 4. Crystallography & Experiment

▶

5. Entities and Polymers Entities & Polymers (3)

Entity 1 Entity 1 polymer

Description description	Mitotic spindle assembly checkpoint protein MAD2A
Molecular weight formula_weight	23447.8 kDa
Mutation mutation	R133A
Source method src_method	man
Copy count entity_count	4

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B,C,D
Atom count atom_count	9928

MALQLSREQGITLRGSAEIVAEFFSFGINSILYQRGIYPSETFTRVQKYGLTLLVTTDLELIKYLNNVVEQLKDWLYKCSVQKLVVVISNIESGEVLERWQFDIECDKTAKDDSAPREKSQKAIQDEIRSVIAQITATVTFLPLLEVSCSFDLLIYTDKDLVVPEKWEESGPQFITNSEEVRLRSFTTTIHKVNSMVAYKIPVND

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

Entity 2 Entity 2 polymer

Description description	Mitotic spindle assembly checkpoint protein MAD1
Molecular weight formula_weight	11693.1 kDa
Source method src_method	man
Copy count entity_count	4

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	E,F,G,H

SSAEQSFLFSREEADTLRLKVEELEGERSRLEEEKRMLEAQLERRALQGDYDQSRTKVLHMSLNPTSVARQRLREDHSQLQAECERLRGLLRAMERGGTV

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

Entity 3 Entity 3 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	628

▼

6. Fold Classification (SCOP + CATH) 16 domains

SCOP 2.08 (8 domains)

Domain ID domain_id	d1go4a_
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.135 — The spindle assembly checkpoint protein mad2
Superfamily Superfamily superfamily	d.135.1 — The spindle assembly checkpoint protein mad2
Family Family family	d.135.1.1 — The spindle assembly checkpoint protein mad2

Domain ID domain_id	d1go4b_
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.135 — The spindle assembly checkpoint protein mad2
Superfamily Superfamily superfamily	d.135.1 — The spindle assembly checkpoint protein mad2
Family Family family	d.135.1.1 — The spindle assembly checkpoint protein mad2

Domain ID domain_id	d1go4c_
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.135 — The spindle assembly checkpoint protein mad2
Superfamily Superfamily superfamily	d.135.1 — The spindle assembly checkpoint protein mad2
Family Family family	d.135.1.1 — The spindle assembly checkpoint protein mad2

Domain ID domain_id	d1go4d_
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.135 — The spindle assembly checkpoint protein mad2
Superfamily Superfamily superfamily	d.135.1 — The spindle assembly checkpoint protein mad2
Family Family family	d.135.1.1 — The spindle assembly checkpoint protein mad2

Domain ID domain_id	d1go4e_
Class class	h — Coiled coil proteins
Fold Fold fold	h.1 — Parallel coiled-coil
Superfamily Superfamily superfamily	h.1.22 — Mitotic arrest deficient-like 1, Mad1
Family Family family	h.1.22.1 — Mitotic arrest deficient-like 1, Mad1

Domain ID domain_id	d1go4f_
Class class	h — Coiled coil proteins
Fold Fold fold	h.1 — Parallel coiled-coil
Superfamily Superfamily superfamily	h.1.22 — Mitotic arrest deficient-like 1, Mad1
Family Family family	h.1.22.1 — Mitotic arrest deficient-like 1, Mad1

Domain ID domain_id	d1go4g_
Class class	h — Coiled coil proteins
Fold Fold fold	h.1 — Parallel coiled-coil
Superfamily Superfamily superfamily	h.1.22 — Mitotic arrest deficient-like 1, Mad1
Family Family family	h.1.22.1 — Mitotic arrest deficient-like 1, Mad1

Domain ID domain_id	d1go4h_
Class class	h — Coiled coil proteins
Fold Fold fold	h.1 — Parallel coiled-coil
Superfamily Superfamily superfamily	h.1.22 — Mitotic arrest deficient-like 1, Mad1
Family Family family	h.1.22.1 — Mitotic arrest deficient-like 1, Mad1

CATH v4.4 (8 domains)

Domain ID domain_id	1go4A00
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	900 — Cell Cycle, Spindle Assembly Checkpoint Protein; Chain A
Homologous superfamily homologous superfamily	10 — HORMA domain

Domain ID domain_id	1go4B00
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	900 — Cell Cycle, Spindle Assembly Checkpoint Protein; Chain A
Homologous superfamily homologous superfamily	10 — HORMA domain

Domain ID domain_id	1go4C00
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	900 — Cell Cycle, Spindle Assembly Checkpoint Protein; Chain A
Homologous superfamily homologous superfamily	10 — HORMA domain

Domain ID domain_id	1go4D00
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	900 — Cell Cycle, Spindle Assembly Checkpoint Protein; Chain A
Homologous superfamily homologous superfamily	10 — HORMA domain

Domain ID domain_id	1go4E00
Class class	6 — Special
Architecture architecture	10 — Helix non-globular
Topology topology	250 — Single alpha-helices involved in coiled-coils or other helix-helix interfaces
Homologous superfamily homologous superfamily	90 —

Domain ID domain_id	1go4F00
Class class	6 — Special
Architecture architecture	10 — Helix non-globular
Topology topology	250 — Single alpha-helices involved in coiled-coils or other helix-helix interfaces
Homologous superfamily homologous superfamily	90 —

Domain ID domain_id	1go4G00
Class class	6 — Special
Architecture architecture	10 — Helix non-globular
Topology topology	250 — Single alpha-helices involved in coiled-coils or other helix-helix interfaces
Homologous superfamily homologous superfamily	90 —

Domain ID domain_id	1go4H00
Class class	6 — Special
Architecture architecture	10 — Helix non-globular
Topology topology	250 — Single alpha-helices involved in coiled-coils or other helix-helix interfaces
Homologous superfamily homologous superfamily	90 —

▶

Unit-cell length a length_a	111.037 Å
Unit-cell length b length_b	63.023 Å
Unit-cell length c length_c	139.511 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	111.65 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	8

Space group space_group	P 1 21 1
Space-group number int_tables_number	4
Crystal system crystal_system	—

Resolution resolution	2.050 Å
Low-resolution limit resolution_low	24.500 Å
R factor r_factor	0.2400
R_work r_work	0.2400
R_free r_free	0.2680

Crystal structure of Mad1-Mad2 reveals a conserved Mad2 binding motif in Mad1 and Cdc20.

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

Mitotic spindle assembly checkpoint protein MAD2A

State in the Current Structure

Other States of the Same Protein in the Database

Mitotic spindle assembly checkpoint protein MAD1

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

1go4__assembly_1__model_1

1go4__assembly_1__model_1 | I(q)

1go4__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

Diffraction experiment Diffraction

5. Entities and Polymers Entities & Polymers (3)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 water

6. Fold Classification (SCOP + CATH) 16 domains

SCOP 2.08 (8 domains)

CATH v4.4 (8 domains)

7. Citations (1)

Crystal structure of Mad1-Mad2 reveals a conserved Mad2 binding motif in Mad1 and Cdc20.

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

Mitotic spindle assembly checkpoint protein MAD2A

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

Mitotic spindle assembly checkpoint protein MAD1

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

1go4__assembly_1__model_1

1go4__assembly_1__model_1 | I(q)

1go4__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

Diffraction experiment Diffraction

5. Entities and Polymers Entities & Polymers (3)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 water

6. Fold Classification (SCOP + CATH) 16 domains

SCOP 2.08 (8 domains)

CATH v4.4 (8 domains)

7. Citations (1)