Annotations: 8ACI

Structure of ARG-117 Fab in complex with a fragment of complement C2, neutral pH

External Resource: Annotation

Domain Annotation: ECOD Classification
SAbDab Antibody Annotation
Thera-SAbDab Antibody Annotation
Protein Family Annotation
Gene Ontology: Gene Product Annotation
InterPro: Protein Family Classification
Pharos: Disease Associations

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
A	Ribosomal_L27A, Ribosomal_L18	e8aciA1	A: alpha arrays	X: HTH	H: HTH	T: Three-helical HTH	F: Ribosomal_L27A, Ribosomal_L18	ECOD (v295)
B [auth H]	Ribosomal_L27A, Ribosomal_L18	e8aciH1	A: alpha arrays	X: HTH	H: HTH	T: Three-helical HTH	F: Ribosomal_L27A, Ribosomal_L18	ECOD (v295)
C [auth K]	Ribosomal_L27A, Ribosomal_L18	e8aciK1	A: alpha arrays	X: HTH	H: HTH	T: Three-helical HTH	F: Ribosomal_L27A, Ribosomal_L18	ECOD (v295)
D [auth L]	Ribosomal_L27A, Ribosomal_L18	e8aciL1	A: alpha arrays	X: HTH	H: HTH	T: Three-helical HTH	F: Ribosomal_L27A, Ribosomal_L18	ECOD (v295)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
B [auth H]	Heavy Chain	IGHV1	-	complement c2b fragment	SAbDab (2026-06-26)
C [auth K]	Heavy Chain	IGHV1	-	-	SAbDab (2026-06-26)
D [auth L]	Light Chain	IGKV3	Kappa	complement c2b fragment	SAbDab (2026-06-26)

Thera-SAbDab Antibody Annotation Thera-SAbDab Database Homepage

Chain	Name	Target	Provenance Source
B [auth H]	Empasiprubart	C2	Therapeutic SAbDab (2026-06-26)
D [auth L]	Empasiprubart	C2	Therapeutic SAbDab (2026-06-26)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A	PF00084	Sushi repeat (SCR repeat) (Sushi)	Sushi repeat (SCR repeat)		Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
A	Complement C2b fragment	peptidase activity catalytic activity, acting on a protein serine hydrolase activity serine-type peptidase activity hydrolase activity serine-type endopeptidase activity catalytic activity endopeptidase activity cation binding ion binding binding metal ion binding small molecule binding	adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity humoral immune response response to stimulus positive regulation of biological process positive regulation of response to stimulus complement activation humoral immune response mediated by circulating immunoglobulin positive regulation of immune response leukocyte mediated immunity regulation of immune system process positive regulation of immune system process complement activation, classical pathway regulation of biological process adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity humoral immune response response to stimulus positive regulation of biological process positive regulation of response to stimulus complement activation humoral immune response mediated by circulating immunoglobulin positive regulation of immune response leukocyte mediated immunity regulation of immune system process positive regulation of immune system process complement activation, classical pathway regulation of biological process immune response biological regulation immunoglobulin mediated immune response adaptive immune response immune effector process regulation of response to stimulus immune system process B cell mediated immunity regulation of immune response activation of immune response biological process involved in interspecies interaction between organisms 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 complement activation, GZMK pathway defense response to other organism response to bacterium import into cell regulation of localization positive regulation of cellular component organization regulation of cellular process regulation of cellular component organization transport positive regulation of apoptotic cell clearance vesicle-mediated transport cellular component organization localization positive regulation of endocytosis phagocytosis apoptotic cell clearance cellular component organization or biogenesis positive regulation of cellular process regulation of endocytosis regulation of transport regulation of phagocytosis regulation of vesicle-mediated transport establishment of localization positive regulation of phagocytosis positive regulation of transport cellular process endocytosis regulation of apoptotic cell clearance proteolysis metabolic process primary metabolic process protein metabolic process macromolecule metabolic process	cellular anatomical structure extracellular region extracellular exosome membrane-bounded organelle extracellular vesicle extracellular organelle organelle vesicle extracellular membrane-bounded organelle cell surface other organism part symbiont cell surface
B [auth H]	ARGX-117 Fab heavy chain	-	-	-
C [auth K]	nanobody specific for kappa light chain of Fab	-	-	-
D [auth L]	ARGX-117 Fab light chain	-	-	-

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A	IPR011360	Complement B/C2	Family
A	IPR009003	Peptidase S1, PA clan	Homologous Superfamily
A	IPR036465	von Willebrand factor A-like domain superfamily	Homologous Superfamily
A	IPR001314	Peptidase S1A, chymotrypsin family	Family
A	IPR033116	Serine proteases, trypsin family, serine active site	Active Site
A	IPR001254	Serine proteases, trypsin domain	Domain
A	IPR018114	Serine protease-like, trypsin family, histidine active site	Active Site
A	IPR002035	von Willebrand factor, type A	Domain
A	IPR000436	Sushi/SCR/CCP domain	Domain
A	IPR043504	Peptidase_S1_PA_chymotrypsin	Unknown
A	IPR035976	Sushi/SCR/CCP superfamily	Homologous Superfamily

Pharos: Disease Associations Pharos Homepage Annotation

Chains	Drug Target	Associated Disease
A	: P06681	complement component 2 deficiency age-related macular degeneration IgA glomerulonephritis dermatomyositis irritant dermatitis MACULAR DEGENERATION, AGE-RELATED, 14 neuromyelitis optica psoriatic arthritis squamous cell lung carcinoma ulcerative colitis autism spectrum disorder Crohn disease endometriosis heart disease lung carcinoma complement component 2 deficiency age-related macular degeneration IgA glomerulonephritis dermatomyositis irritant dermatitis MACULAR DEGENERATION, AGE-RELATED, 14 neuromyelitis optica psoriatic arthritis squamous cell lung carcinoma ulcerative colitis autism spectrum disorder Crohn disease endometriosis heart disease lung carcinoma non-alcoholic fatty liver disease retinal degeneration subependymal giant cell astrocytoma age related macular degeneration 14 vitiligo cervical cancer eosinophilic esophagitis hepatitis B virus infection macular degeneration membranous glomerulonephritis non-small cell lung carcinoma skin basal cell carcinoma systemic lupus erythematosus wet macular degeneration Hashimoto thyroiditis hypertensive disorder juvenile dermatomyositis

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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.