Annotations: 6CXO

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
A	PF01823	e6cxoA3	A: beta complex topology	X: Membrane attack complex/perforin (MACPF) and cholesterol-dependent cytolysin (CDC) domains (From Topology)	H: Membrane attack complex/perforin (MACPF) and cholesterol-dependent cytolysin (CDC) domains (From Topology)	T: Membrane attack complex/perforin (MACPF) and cholesterol-dependent cytolysin (CDC) domains	F: PF01823	ECOD (1.6)
A	F_UNCLASSIFIED	e6cxoA4	A: few secondary structure elements	X: EGF-like	H: EGF-related	T: EGF/Laminin	F: F_UNCLASSIFIED	ECOD (1.6)
A	PF00057	e6cxoA2	A: few secondary structure elements	X: EGF-like	H: LDL receptor-like module (From Topology)	T: LDL receptor-like module	F: PF00057	ECOD (1.6)
A	PF00090	e6cxoA1	A: few secondary structure elements	X: TSP-1 type 1 repeat (From Topology)	H: TSP-1 type 1 repeat (From Topology)	T: TSP-1 type 1 repeat	F: PF00090	ECOD (1.6)
B	PF01823	e6cxoB1	A: beta complex topology	X: Membrane attack complex/perforin (MACPF) and cholesterol-dependent cytolysin (CDC) domains (From Topology)	H: Membrane attack complex/perforin (MACPF) and cholesterol-dependent cytolysin (CDC) domains (From Topology)	T: Membrane attack complex/perforin (MACPF) and cholesterol-dependent cytolysin (CDC) domains	F: PF01823	ECOD (1.6)
B	F_UNCLASSIFIED	e6cxoB4	A: few secondary structure elements	X: EGF-like	H: EGF-related	T: EGF/Laminin	F: F_UNCLASSIFIED	ECOD (1.6)
B	PF00057	e6cxoB3	A: few secondary structure elements	X: EGF-like	H: LDL receptor-like module (From Topology)	T: LDL receptor-like module	F: PF00057	ECOD (1.6)
B	PF00090	e6cxoB2	A: few secondary structure elements	X: TSP-1 type 1 repeat (From Topology)	H: TSP-1 type 1 repeat (From Topology)	T: TSP-1 type 1 repeat	F: PF00090	ECOD (1.6)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A, B	PF00090	Thrombospondin type 1 domain (TSP_1)	Thrombospondin type 1 domain	-	Domain
A, B	PF01823	MAC/Perforin domain (MACPF)	MAC/Perforin domain	The membrane-attack complex (MAC) of the complement system forms transmembrane channels. These channels disrupt the phospholipid bilayer of target cells, leading to cell lysis and death. A number of proteins participate in the assembly of the MAC. Fr ...	The membrane-attack complex (MAC) of the complement system forms transmembrane channels. These channels disrupt the phospholipid bilayer of target cells, leading to cell lysis and death. A number of proteins participate in the assembly of the MAC. Freshly activated C5b binds to C6 to form a C5b-6 complex, then to C7 forming the C5b-7 complex. The C5b-7 complex binds to C8, which is composed of three chains (alpha, beta, and gamma), thus forming the C5b-8 complex. C5b-8 subsequently binds to C9 and acts as a catalyst in the polymerisation of C9. Active MAC has a subunit composition of C5b-C6-C7-C8-C9{n}. Perforin is a protein found in cytolytic T-cell and killer cells. In the presence of calcium, perforin polymerises into transmembrane tubules and is capable of lysing, non-specifically, a variety of target cells. There are a number of regions of similarity in the sequences of complement components C6, C7, C8-alpha, C8-beta, C9 and perforin. The X-ray crystal structure of a MACPF domain reveals that it shares a common fold with bacterial cholesterol dependent cytolysins (Pfam:PF01289) such as perfringolysin O. Three key pieces of evidence suggests that MACPF domains and CDCs are homologous: Functional similarity (pore formation), conservation of three glycine residues at a hinge in both families and conservation of a complex core fold [1].	Domain
A, B	PF00057	Low-density lipoprotein receptor domain class A (Ldl_recept_a)	Low-density lipoprotein receptor domain class A	-	Repeat

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
A, B	Complement component C9	-	regulation of biological process response to stimulus immune response biological regulation positive regulation of biological process positive regulation of response to stimulus positive regulation of immune response regulation of response to stimulus immune system process regulation of immune response regulation of immune system process positive regulation of immune system process adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity regulation of biological process response to stimulus immune response biological regulation positive regulation of biological process positive regulation of response to stimulus positive regulation of immune response regulation of response to stimulus immune system process regulation of immune response regulation of immune system process positive regulation of immune system process adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity humoral immune response complement activation humoral immune response mediated by circulating immunoglobulin leukocyte mediated immunity complement activation, classical pathway immunoglobulin mediated immune response adaptive immune response immune effector process B cell mediated immunity activation of immune response biological process involved in interspecies interaction between organisms cellular process disruption of cell in another organism disruption of anatomical structure in another organism killing of cells of another organism cell killing complement activation, alternative pathway response to biotic stimulus response to stress innate immune response response to external biotic stimulus response to other organism defense response defense response to symbiont response to external stimulus defense response to other organism cellular component organization cellular component biogenesis cellular component assembly protein-containing complex organization protein complex oligomerization protein-containing complex assembly protein homooligomerization cellular component organization or biogenesis	cell periphery protein-containing complex plasma membrane protein complex membrane plasma membrane membrane protein complex pore complex cellular anatomical entity membrane attack complex other organism cell membrane other organism part extracellular region extracellular space

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A, B	IPR000884	Thrombospondin type-1 (TSP1) repeat	Repeat
A, B	IPR020864	Membrane attack complex component/perforin (MACPF) domain	Domain
A, B	IPR002172	Low-density lipoprotein (LDL) receptor class A repeat	Repeat
A, B	IPR036383	Thrombospondin type-1 (TSP1) repeat superfamily	Homologous Superfamily
A, B	IPR001862	Membrane attack complex component/perforin/complement C9	Family
A, B	IPR009030	Growth factor receptor cysteine-rich domain superfamily	Homologous Superfamily
A, B	IPR023415	Low-density lipoprotein (LDL) receptor class A, conserved site	Conserved Site
A, B	IPR036055	LDL receptor-like superfamily	Homologous Superfamily
A, B	IPR020863	Membrane attack complex component/perforin domain, conserved site	Conserved Site

Membrane Protein Annotation: mpstruc mpstruc Database Homepage

Chains	Resource Link	Group	Subgroup	Protein
A, B	mpstruc	TRANSMEMBRANE PROTEINS: BETA-BARREL	Adventitious Membrane Proteins: Beta-sheet Pore-forming Toxins/Attack Complexes	monomeric C9 component of the complement membrane attack Complex

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 R01GM133198.