Annotations: 9V31

Human claudin 18.2 (dimer form) in complex with the Fab fragment of Osemitamab (TST001)

External Resource: Annotation

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

Thera-SAbDab Antibody Annotation Thera-SAbDab Database Homepage

Chain	Name	Target	Provenance Source
C [auth L], E [auth D]	Osemitamab	CLDN18	Therapeutic SAbDab (2026-08-21)
B [auth H], D [auth C]	Osemitamab	CLDN18	Therapeutic SAbDab (2026-08-21)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A, F [auth B]	PF00822	PMP-22/EMP/MP20/Claudin family (PMP22_Claudin)	PMP-22/EMP/MP20/Claudin family	-	Family

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
C [auth L], E [auth D]	Fab of Osemitamab (TST001) - Light chain	-	-	-
B [auth H], D [auth C]	Fab of Osemitamab (TST001) - Heavy chain	-	-	-
A, F [auth B]	Isoform A2 of Claudin-18	structural molecule activity identical protein binding protein binding binding	developmental process multicellular organismal process developmental growth growth organ growth cell population proliferation cellular process epithelial cell proliferation tight junction organization cellular component organization cellular component biogenesis cell junction organization cellular component assembly tight junction assembly developmental process multicellular organismal process developmental growth growth organ growth cell population proliferation cellular process epithelial cell proliferation tight junction organization cellular component organization cellular component biogenesis cell junction organization cellular component assembly tight junction assembly cell junction assembly cellular component organization or biogenesis cell-cell junction assembly cell-cell junction organization calcium-independent cell-cell adhesion cell adhesion cell-cell adhesion cellular response to stimulus response to stimulus response to endogenous stimulus response to estrogen cellular response to estrogen stimulus cellular response to endogenous stimulus cellular response to chemical stimulus response to hormone response to chemical cellular response to hormone stimulus localization epithelial fluid transport transport transepithelial transport fluid transport establishment of localization regulation of localization regulation of biological process regulation of protein localization biological regulation negative regulation of biological process regulation of protein localization to nucleus protein localization to nucleus negative regulation of protein localization to nucleus macromolecule localization protein localization to organelle intracellular protein localization negative regulation of protein localization tube development animal organ development respiratory tube development multicellular organism development anatomical structure development lung development respiratory system development lung alveolus development animal gross anatomical part developmental process system development response to alcohol response to oxygen-containing compound response to ethanol	cell-cell junction cellular anatomical structure anchoring junction cell junction apical junction complex bicellular tight junction tight junction cell periphery plasma membrane membrane lateral plasma membrane

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A, F [auth B]	IPR006187	Claudin	Family
A, F [auth B]	IPR017974	Claudin, conserved site	Conserved Site
A, F [auth B]	IPR003928	Claudin-18	Family
A, F [auth B]	IPR004031	PMP-22/EMP/MP20/Claudin	Family

Pharos: Disease Associations Pharos Homepage Annotation

Chains	Drug Target	Associated Disease
A, F [auth B]	: P56856	Barrett esophagus lung cancer non-small cell lung carcinoma pancreatic intraductal papillary-mucinous neoplasm esophageal adenocarcinoma lung carcinoma pancreatic ductal adenocarcinoma pancreatic intraductal papillary-mucinous neoplasm with low grade dysplasia lung adenocarcinoma malignant pancreatic neoplasm pancreatic intraductal papillary-mucinous carcinoma psoriasis

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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.