Annotations: 5OCK

Crystal structure of ACPA E4 in complex with CEP1

External Resource: Annotation

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

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
A [auth L]	Chlorophyllase2	e5ockL1	A: a/b three-layered sandwiches	X: PriB N-terminal domain-like	H: gp11/gp12 receptor-binding domain	T: gp11/gp12 receptor-binding domain	F: Chlorophyllase2	ECOD (v294.1)
B [auth H]	ATG101	e5ockH1	A: a/b three-layered sandwiches	X: PriB N-terminal domain-like	H: ADP-ribosylation	T: ADP-ribosylation	F: ATG101	ECOD (v294.1)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
A [auth L]	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (utative)
B [auth H]	2.60.40.10	Mainly Beta	Sandwich	Immunoglobulin-like	Immunoglobulins	CATH (utative)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
A [auth L]	Light Chain	IGLV1	Lambda	cep1 peptide (from enolase)	SAbDab (2026-04-24)
B [auth H]	Heavy Chain	IGHV4	-	cep1 peptide (from enolase)	SAbDab (2026-04-24)

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
A [auth L]	Human ACPA E4 Fab fragment - Light chain	-	-	-
C [auth A]	CEP1 peptide (from enolase)	transcription factor binding transcription coregulator binding transcription corepressor binding protein binding binding hydro-lyase activity lyase activity phosphopyruvate hydratase activity catalytic activity carbon-oxygen lyase activity DNA-binding transcription factor activity, RNA polymerase II-specific DNA-binding transcription repressor activity, RNA polymerase II-specific transcription regulator activity DNA-binding transcription repressor activity transcription factor binding transcription coregulator binding transcription corepressor binding protein binding binding hydro-lyase activity lyase activity phosphopyruvate hydratase activity catalytic activity carbon-oxygen lyase activity DNA-binding transcription factor activity, RNA polymerase II-specific DNA-binding transcription repressor activity, RNA polymerase II-specific transcription regulator activity DNA-binding transcription repressor activity DNA-binding transcription factor activity RNA binding nucleic acid binding enzyme binding GTPase binding DNA binding sequence-specific DNA binding sequence-specific double-stranded DNA binding transcription cis-regulatory region binding double-stranded DNA binding RNA polymerase II transcription regulatory region sequence-specific DNA binding transcription regulatory region nucleic acid binding cation binding magnesium ion binding ion binding metal ion binding small molecule binding transcription corepressor activity transcription coregulator activity identical protein binding protein homodimerization activity protein dimerization activity cell adhesion molecule binding cadherin binding	regulation of cellular process negative regulation of biological process RNA metabolic process regulation of primary metabolic process negative regulation of RNA biosynthetic process RNA biosynthetic process nucleobase-containing compound metabolic process DNA-templated transcription nucleic acid biosynthetic process regulation of RNA metabolic process negative regulation of cellular process negative regulation of nucleobase-containing compound metabolic process regulation of nucleobase-containing compound metabolic process regulation of RNA biosynthetic process regulation of cellular process negative regulation of biological process RNA metabolic process regulation of primary metabolic process negative regulation of RNA biosynthetic process RNA biosynthetic process nucleobase-containing compound metabolic process DNA-templated transcription nucleic acid biosynthetic process regulation of RNA metabolic process negative regulation of cellular process negative regulation of nucleobase-containing compound metabolic process regulation of nucleobase-containing compound metabolic process regulation of RNA biosynthetic process negative regulation of macromolecule metabolic process regulation of biosynthetic process negative regulation of DNA-templated transcription regulation of biological process negative regulation of metabolic process biological regulation primary metabolic process regulation of macromolecule metabolic process nucleobase-containing compound biosynthetic process gene expression macromolecule biosynthetic process nucleic acid metabolic process regulation of gene expression biosynthetic process negative regulation of biosynthetic process negative regulation of macromolecule biosynthetic process metabolic process cellular process regulation of macromolecule biosynthetic process macromolecule metabolic process regulation of DNA-templated transcription regulation of metabolic process negative regulation of RNA metabolic process cellular response to stimulus response to stimulus cellular response to oxygen levels cellular response to hypoxia regulation of cellular response to stress regulation of signal transduction regulation of programmed cell death intracellular signal transduction cell communication negative regulation of apoptotic signaling pathway signal transduction intrinsic apoptotic signaling pathway response to decreased oxygen levels negative regulation of programmed cell death regulation of apoptotic process cell death negative regulation of apoptotic process intrinsic apoptotic signaling pathway in response to hypoxia response to hypoxia regulation of response to stimulus response to chemical response to oxygen levels response to abiotic stimulus regulation of apoptotic signaling pathway regulation of cellular response to hypoxia signaling negative regulation of signaling negative regulation of intracellular signal transduction cellular response to decreased oxygen levels regulation of intrinsic apoptotic signaling pathway negative regulation of cell communication cellular response to stress regulation of intracellular signal transduction response to stress regulation of response to stress regulation of signaling negative regulation of response to stimulus regulation of hypoxia-induced intrinsic apoptotic signaling pathway negative regulation of signal transduction negative regulation of cellular response to hypoxia apoptotic signaling pathway negative regulation of intrinsic apoptotic signaling pathway cellular response to chemical stimulus negative regulation of hypoxia-induced intrinsic apoptotic signaling pathway regulation of cell communication apoptotic process programmed cell death regulation of protein maturation positive regulation of protein maturation positive regulation of protein metabolic process positive regulation of biological process positive regulation of macromolecule biosynthetic process positive regulation of protein processing protein maturation positive regulation of metabolic process positive regulation of plasminogen activation regulation of proteolysis positive regulation of biosynthetic process proteolysis regulation of plasminogen activation positive regulation of macromolecule metabolic process protein metabolic process plasminogen activation positive regulation of cellular process zymogen activation regulation of protein metabolic process positive regulation of gene expression positive regulation of proteolysis regulation of protein processing protein processing regulation of growth regulation of cellular component organization growth negative regulation of cell growth regulation of cell growth cell growth cellular component organization negative regulation of growth cellular component organization or biogenesis multicellular organismal process system process regulation of system process muscle contraction muscle system process regulation of muscle system process regulation of muscle contraction positive regulation of muscle contraction positive regulation of multicellular organismal process regulation of multicellular organismal process ribonucleotide catabolic process pyridine nucleotide catabolic process aerobic respiration oxoacid metabolic process carbohydrate catabolic process carbohydrate derivative metabolic process organophosphate catabolic process nucleoside phosphate catabolic process organic acid metabolic process glycolytic process phosphate-containing compound metabolic process pyridine-containing compound metabolic process small molecule metabolic process purine ribonucleotide catabolic process phosphorus metabolic process nucleoside phosphate metabolic process nicotinamide nucleotide metabolic process pyruvate metabolic process purine nucleoside diphosphate metabolic process purine-containing compound catabolic process nucleotide metabolic process nucleobase-containing compound catabolic process nucleoside diphosphate metabolic process purine nucleoside diphosphate catabolic process nucleoside diphosphate catabolic process nucleoside triphosphate metabolic process monocarboxylic acid metabolic process purine ribonucleotide metabolic process pyridine-containing compound catabolic process ribose phosphate metabolic process cellular respiration catabolic process ATP metabolic process energy derivation by oxidation of organic compounds purine nucleotide metabolic process ribonucleotide metabolic process nucleobase-containing small molecule metabolic process purine ribonucleoside triphosphate metabolic process ribonucleoside diphosphate metabolic process ribonucleoside diphosphate catabolic process nucleotide catabolic process purine nucleoside triphosphate metabolic process purine nucleotide catabolic process carbohydrate metabolic process carbohydrate derivative catabolic process ADP catabolic process carboxylic acid metabolic process generation of precursor metabolites and energy purine-containing compound metabolic process ADP metabolic process organophosphate metabolic process purine ribonucleoside diphosphate metabolic process purine ribonucleoside diphosphate catabolic process monosaccharide metabolic process small molecule biosynthetic process carbohydrate biosynthetic process hexose metabolic process monosaccharide biosynthetic process gluconeogenesis hexose biosynthetic process glucose metabolic process biological process involved in interspecies interaction between organisms response to other organism response to external stimulus response to external biotic stimulus response to virus response to biotic stimulus nucleotide biosynthetic process purine ribonucleotide biosynthetic process positive regulation of phosphate metabolic process purine ribonucleoside triphosphate biosynthetic process positive regulation of nucleotide biosynthetic process regulation of nucleotide biosynthetic process regulation of ATP metabolic process ribonucleotide biosynthetic process purine nucleoside triphosphate biosynthetic process regulation of small molecule metabolic process positive regulation of purine nucleotide biosynthetic process regulation of nucleotide metabolic process ribose phosphate biosynthetic process positive regulation of phosphorus metabolic process regulation of purine nucleotide metabolic process ribonucleoside triphosphate biosynthetic process positive regulation of ATP metabolic process organophosphate biosynthetic process nucleoside phosphate biosynthetic process regulation of phosphorus metabolic process purine nucleotide biosynthetic process ATP biosynthetic process positive regulation of nucleotide metabolic process purine-containing compound biosynthetic process carbohydrate derivative biosynthetic process regulation of purine nucleotide biosynthetic process nucleoside triphosphate biosynthetic process positive regulation of purine nucleotide metabolic process positive regulation of ATP biosynthetic process regulation of ATP biosynthetic process positive regulation of small molecule metabolic process glucose catabolic process to pyruvate hexose catabolic process glucose catabolic process monosaccharide catabolic process small molecule catabolic process canonical glycolysis glycolytic process through glucose-6-phosphate glycolytic process through fructose-6-phosphate transcription by RNA polymerase II regulation of transcription by RNA polymerase II negative regulation of transcription by RNA polymerase II	M band intracellular anatomical structure intracellular membraneless organelle sarcomere intracellular organelle cellular anatomical structure organelle membraneless organelle contractile muscle fiber A band cytoplasm supramolecular fiber myofibril supramolecular polymer M band intracellular anatomical structure intracellular membraneless organelle sarcomere intracellular organelle cellular anatomical structure organelle membraneless organelle contractile muscle fiber A band cytoplasm supramolecular fiber myofibril supramolecular polymer supramolecular complex membrane cell periphery cell cortex extracellular exosome membrane-bounded organelle extracellular vesicle extracellular organelle extracellular region vesicle extracellular membrane-bounded organelle cell surface cytosol plasma membrane protein-containing complex catalytic complex phosphopyruvate hydratase complex nuclear outer membrane nuclear membrane nucleus organelle outer membrane intracellular membrane-bounded organelle endomembrane system organelle envelope bounding membrane of organelle nuclear outer membrane-endoplasmic reticulum membrane network nuclear envelope outer membrane organelle membrane
B [auth H]	Human ACPA E4 Fab fragment - Heavy chain	-	-	-

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
C [auth A]	IPR020811	Enolase, N-terminal	Domain
C [auth A]	IPR036849	Enolase-like, C-terminal domain superfamily	Homologous Superfamily
C [auth A]	IPR020809	Enolase, conserved site	Conserved Site
C [auth A]	IPR020810	Enolase, C-terminal TIM barrel domain	Domain
C [auth A]	IPR000941	Enolase	Family
C [auth A]	IPR029017	Enolase-like, N-terminal	Homologous Superfamily

Pharos: Disease Associations Pharos Homepage Annotation

Chains	Drug Target	Associated Disease
C [auth A]	: P06733	Alzheimer disease rheumatoid arthritis non-small cell lung carcinoma squamous cell carcinoma Mammary Neoplasms, Experimental esophageal cancer osteoporosis carcinoma acute coronary syndrome granular cell carcinoma perinatal necrotizing enterocolitis sarcomatoid carcinoma tubular adenocarcinoma adenocarcinoma lung adenocarcinoma Alzheimer disease rheumatoid arthritis non-small cell lung carcinoma squamous cell carcinoma Mammary Neoplasms, Experimental esophageal cancer osteoporosis carcinoma acute coronary syndrome granular cell carcinoma perinatal necrotizing enterocolitis sarcomatoid carcinoma tubular adenocarcinoma adenocarcinoma lung adenocarcinoma male infertility breast carcinoma cribriform carcinoma diabetes mellitus myopathy neoplasm of esophagus osteoarthritis gastric neoplasm osteosarcoma pancreatic intraductal papillary-mucinous carcinoma limb-girdle muscular dystrophy lung cancer Becker muscular dystrophy cribriform carcinoma of breast necrotizing enterocolitis drug-induced liver injury osteoarthritis susceptibility 1 ovarian cancer hepatocellular carcinoma lymphoplasmacytic lymphoma breast cancer malignant pancreatic neoplasm congenital anemia mammary neoplasms, animal Duchenne muscular dystrophy oral cavity neoplasm gastric cancer pancreatic ductal adenocarcinoma hereditary diffuse gastric adenocarcinoma plasma cell myeloma psoriasis undifferentiated carcinoma

Protein Modification Annotation

Modified Residue(s)
Chain	Residue(s)	Description
A [auth L]	PCA	Parent Component: GLN : AA0031 : 2-pyrrolidone-5-carboxylic acid (Gln) MOD:00040 , 2-pyrrolidone-5-carboxylic acid (Glu) MOD:00420
C [auth A]	ACA	: AA0031 : 2-pyrrolidone-5-carboxylic acid (Gln) MOD:00040 , 2-pyrrolidone-5-carboxylic acid (Glu) MOD:00420
C [auth A]	CIR	Parent Component: ARG : AA0031 , AA0214 : 2-pyrrolidone-5-carboxylic acid (Gln) MOD:00040 , 2-pyrrolidone-5-carboxylic acid (Glu) MOD:00420 , L-citrulline MOD:00219
B [auth H]	PCA	Parent Component: GLN : AA0031 , AA0214 , AA0031 : 2-pyrrolidone-5-carboxylic acid (Gln) MOD:00040 , 2-pyrrolidone-5-carboxylic acid (Glu) MOD:00420 , L-citrulline MOD:00219 , 2-pyrrolidone-5-carboxylic acid (Gln) MOD:00040 , 2-pyrrolidone-5-carboxylic acid (Glu) MOD:00420

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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.