Annotations: 8XS1

Crystal structure of Fab fragment of anti-osteocalcin antibody KTM219 complexed with C-terminal peptide antigen

External Resource: Annotation

Domain Annotation: ECOD Classification
SAbDab Antibody 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)
B [auth L]	UCR_hinge	e8xs1L1	A: alpha arrays	X: HTH	H: HTH	T: Three-helical HTH	F: UCR_hinge	ECOD (v295)
A [auth H]	UCR_hinge	e8xs1H1	A: alpha arrays	X: HTH	H: HTH	T: Three-helical HTH	F: UCR_hinge	ECOD (v295)

SAbDab Antibody Annotation SAbDab Database Homepage

Chain	Chain Class	Chain Subclass	Chain Type	Antigen Name(s)	Provenance Source
B [auth L]	Light Chain	IGKV1	Kappa	osteocalcin	SAbDab (2026-06-26)
A [auth H]	Heavy Chain	IGHV1	-	osteocalcin	SAbDab (2026-06-26)

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
C [auth A]	Osteocalcin	structural molecule activity structural constituent of bone cation binding ion binding binding calcium ion binding metal ion binding small molecule binding hormone activity molecular function activator activity molecular function regulator activity signaling receptor regulator activity receptor ligand activity signaling receptor activator activity structural molecule activity structural constituent of bone cation binding ion binding binding calcium ion binding metal ion binding small molecule binding hormone activity molecular function activator activity molecular function regulator activity signaling receptor regulator activity receptor ligand activity signaling receptor activator activity hydroxyapatite binding	response to stimulus response to chemical response to xenobiotic stimulus developmental process multicellular organism development multicellular organismal process head development central nervous system development anatomical structure development animal organ development brain development nervous system development system development ossification response to stimulus response to chemical response to xenobiotic stimulus developmental process multicellular organism development multicellular organismal process head development central nervous system development anatomical structure development animal organ development brain development nervous system development system development ossification bone mineralization biomineral tissue development tissue development skeletal system development response to ketone response to lipid response to oxygen-containing compound response to testosterone bone development regulation of multicellular organismal development regulation of biological process negative regulation of bone development regulation of developmental process negative regulation of developmental process biological regulation negative regulation of biological process regulation of bone development regulation of multicellular organismal process negative regulation of multicellular organismal process system process nervous system process cognition homeostatic process regulation of bone remodeling tissue homeostasis regulation of tissue remodeling regulation of bone resorption bone resorption multicellular organismal-level homeostasis tissue remodeling bone remodeling anatomical structure homeostasis regulation of biomineral tissue development regulation of bone mineralization regulation of ossification response to metal ion response to zinc ion cellular response to stimulus response to nutrient levels response to zinc ion starvation cellular response to starvation response to metal ion starvation cellular response to nutrient levels cellular response to stress response to stress cellular process response to starvation cellular response to zinc ion starvation cell population proliferation type B pancreatic cell proliferation epithelial cell proliferation cell adhesion cellular response to nitrogen compound regulation of cellular process response to endogenous stimulus response to peptide hormone cellular response to peptide hormone stimulus response to nitrogen compound regulation of cellular response to insulin stimulus cellular response to oxygen-containing compound cellular response to endogenous stimulus cellular response to chemical stimulus response to hormone regulation of response to stimulus response to insulin cellular response to insulin stimulus cellular response to hormone stimulus response to abiotic stimulus response to gravity response to peptide response to cytokine response to macrophage colony-stimulating factor response to phenylpropanoid response to hydroxyisoflavone regulation of steroid biosynthetic process ketone metabolic process steroid metabolic process regulation of lipid metabolic process lipid biosynthetic process regulation of primary metabolic process regulation of small molecule metabolic process regulation of testosterone biosynthetic process small molecule metabolic process steroid biosynthetic process regulation of biosynthetic process small molecule biosynthetic process olefinic compound biosynthetic process regulation of ketone biosynthetic process regulation of steroid metabolic process primary metabolic process regulation of ketone metabolic process testosterone biosynthetic process biosynthetic process metabolic process olefinic compound metabolic process regulation of lipid biosynthetic process regulation of metabolic process ketone biosynthetic process lipid metabolic process chemical homeostasis glucose homeostasis carbohydrate homeostasis cellular developmental process cell differentiation osteoblast differentiation response to estrogen response to activity response to corticosteroid response to steroid hormone response to glucocorticoid response to nutrient response to vitamin cellular response to vitamin D response to vitamin D cellular response to vitamin cellular response to lipid cellular response to nutrient response to alcohol response to ethanol response to mechanical stimulus response to external stimulus myeloid leukocyte differentiation regulation of leukocyte differentiation cell development regulation of cell differentiation regulation of cell development regulation of osteoclast differentiation osteoclast differentiation regulation of immune system process hemopoiesis regulation of myeloid cell differentiation regulation of myeloid leukocyte differentiation myeloid cell differentiation immune system process regulation of hemopoiesis leukocyte differentiation cellular response to growth factor stimulus response to growth factor behavior learning or memory positive regulation of cell communication regulation of localization cellular localization transport modulation of chemical synaptic transmission signaling positive regulation of neurotransmitter secretion positive regulation of biological process positive regulation of secretion by cell cell communication localization synaptic signaling regulation of secretion by cell secretion by cell positive regulation of secretion signal release establishment of localization in cell positive regulation of cellular process trans-synaptic signaling regulation of signaling positive regulation of neurotransmitter transport neurotransmitter secretion regulation of transport secretion regulation of neurotransmitter transport export from cell cell-cell signaling positive regulation of synaptic transmission neurotransmitter transport establishment of localization regulation of secretion chemical synaptic transmission signal release from synapse regulation of trans-synaptic signaling positive regulation of transport regulation of neurotransmitter secretion anterograde trans-synaptic signaling regulation of cell communication positive regulation of signaling stem cell differentiation response to vitamin K	somatodendritic compartment cell body cellular anatomical structure perikaryon neuronal cell body cell projection dendrite dendritic tree neuron projection plasma membrane bounded cell projection intracellular anatomical structure cytoplasm membrane-bounded organelle membrane-enclosed lumen somatodendritic compartment cell body cellular anatomical structure perikaryon neuronal cell body cell projection dendrite dendritic tree neuron projection plasma membrane bounded cell projection intracellular anatomical structure cytoplasm membrane-bounded organelle membrane-enclosed lumen intracellular membrane-bounded organelle endomembrane system intracellular organelle lumen endoplasmic reticulum lumen intracellular organelle organelle lumen organelle endoplasmic reticulum vesicle Golgi apparatus Golgi lumen extracellular region
B [auth L]	Light chain of anti-osteocalcin antibody KTM219	-	-	-
A [auth H]	Heavy chain fragment (Fd) chain of anti-osteocalcin antibody KTM219	-	-	-

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
C [auth A]	IPR058704	Osteocalcin-like, C-terminal domain	Domain
C [auth A]	IPR039176	Osteocalcin	Family
C [auth A]	IPR035972	Gamma-carboxyglutamic acid-rich (GLA) domain superfamily	Homologous Superfamily
C [auth A]	IPR000294	Gamma-carboxyglutamic acid-rich (GLA) domain	Domain
C [auth A]	IPR002384	Osteocalcin/matrix Gla protein	Family

Pharos: Disease Associations Pharos Homepage Annotation

Chains	Drug Target	Associated Disease
C [auth A]	: P02818	asthma calcinosis heart valve disease prostate cancer arthritic joint disease cerebrovascular disorder hyperparathyroidism osteonecrosis Prostatic Neoplasms inborn carbohydrate metabolic disorder osteoporosis testicular cancer vitamin K deficiency hemorrhagic disease testicular germ cell tumor

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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.