4NBX | pdb_00004nbx

Crystal Structure of Clostridium difficile Toxin A fragment TcdA-A1 Bound to A20.1 VHH

External Resource: Annotation

Domain Annotation: SCOP/SCOPe Classification
Domain Annotation: ECOD Classification
Domain Annotation: CATH
IMGT Antibody Annotation
SAbDab Antibody Annotation
Gene Ontology: Gene Product Annotation
InterPro: Protein Family Classification

Domain Annotation: SCOP/SCOPe Classification SCOP-e Database Homepage

Chains	Domain Info	Class	Fold	Superfamily	Family	Domain	Species	Provenance Source (Version)
B	d4nbxb_	All beta proteins	Immunoglobulin-like beta-sandwich	Immunoglobulin	V set domains (antibody variable domain-like)	automated matches	(Lama glama ) [TaxId: 9844 ],	SCOPe (2.08)

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
B	EF-hand_1,S_100	e4nbxB1	A: a/b three-layered sandwiches	X: dsRBD-like	H: Peptidyl-tRNA hydrolase domain-like	T: Peptidyl-tRNA hydrolase domain-like	F: EF-hand_1,S_100	ECOD (v294.1)
A	EF-hand_1,S_100	e4nbxA1	A: a/b three-layered sandwiches	X: dsRBD-like	H: Peptidyl-tRNA hydrolase domain-like	T: Peptidyl-tRNA hydrolase domain-like	F: EF-hand_1,S_100	ECOD (v294.1)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
B	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (4.3.0)
A	2.10.270.10	Mainly Beta	Ribbon	left handed beta-beta-3-solenoid	Cholin Binding	CATH (4.3.0)

IMGT Antibody Annotation IMGT Database Homepage

Chain	Protein Name	Description	Organism Name	Gene Allele Name(s)	Domain Name(s)	Receptor Type	Receptor Description	Provenance Source
B	A20.1 VHH	VH	Lama glama (llama)	IGHV3S301, IGHJ401	V-DOMAIN VH	IG	(VH)	IMGT (202611-0)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
B	Heavy Chain	IGHV1	-	tcda	SAbDab (2026-03-27)

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
B	A20.1 VHH	-	-	-
A	TcdA	glycosyltransferase activity transferase activity catalytic activity binding lipid binding toxin activity cysteine-type peptidase activity peptidase activity catalytic activity, acting on a protein hydrolase activity cation binding ion binding metal ion binding small molecule binding	proteolysis metabolic process cellular process primary metabolic process protein metabolic process macromolecule metabolic process	cellular anatomical structure extracellular region host intracellular membrane-bounded organelle host cellular component host intracellular part host cell membrane other organism part host cell cytoplasm part host intracellular organelle host cell endosome membrane host cell cytoplasm host cell part host cell endosome host intracellular region cellular anatomical structure extracellular region host intracellular membrane-bounded organelle host cellular component host intracellular part host cell membrane other organism part host cell cytoplasm part host intracellular organelle host cell endosome membrane host cell cytoplasm host cell part host cell endosome host intracellular region host cell plasma membrane host cell cytosol

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A	IPR038383	CGT/MARTX, cysteine protease (CPD) domain superfamily	Homologous Superfamily
A	IPR024772	TcdA/TcdB toxin, N-terminal helical domain	Domain
A	IPR020974	CGT/MARTX, cysteine protease (CPD) domain	Domain
A	IPR024769	TcdA/TcdB toxin, pore forming domain	Domain
A	IPR029044	Nucleotide-diphospho-sugar transferases	Homologous Superfamily
A	IPR024770	TcdA/TcdB toxin, catalytic glycosyltransferase domain	Domain
A	IPR018337	Cell wall/choline-binding repeat	Repeat

RCSB PDB Core Operations are funded by the U.S. National Science Foundation (DBI-2321666), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM157729. RCSB PDB uses resources of the National Energy Research Scientific Computing Center (NERSC), a Department of Energy User Facility.