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Human Gene CLDN18 (ENST00000183605.10) from GENCODE V50
  Description: claudin 18, transcript variant 1 (from RefSeq NM_016369.4)
Gencode Transcript: ENST00000183605.10
Gencode Gene: ENSG00000066405.15
Transcript (Including UTRs)
   Position: hg38 chr3:138,010,165-138,033,649 Size: 23,485 Total Exon Count: 5 Strand: +
Coding Region
   Position: hg38 chr3:138,010,226-138,031,141 Size: 20,916 Coding Exon Count: 5 

Page IndexSequence and LinksUniProtKB CommentsPrimersMalaCardsCTD
RNA-Seq ExpressionMicroarray ExpressionRNA StructureProtein StructureOther SpeciesGO Annotations
mRNA DescriptionsPathwaysOther NamesMethods
Data last updated at UCSC: 2026-07-12 09:30:09

-  Comments and Description Text from UniProtKB
  ID: CLD18_HUMAN
DESCRIPTION: RecName: Full=Claudin-18;
FUNCTION: Plays a major role in tight junction-specific obliteration of the intercellular space, through calcium- independent cell-adhesion activity (By similarity).
SUBCELLULAR LOCATION: Cell junction, tight junction. Cell membrane; Multi-pass membrane protein.
TISSUE SPECIFICITY: Concentrated at the cell-cell borders of epithelial cells.
SIMILARITY: Belongs to the claudin family.

-  Primer design for this transcript
 

Primer3Plus can design qPCR Primers that straddle exon-exon-junctions, which amplify only cDNA, not genomic DNA.
Click here to load the transcript sequence and exon structure into Primer3Plus

Exonprimer can design one pair of Sanger sequencing primers around every exon, located in non-genic sequence.
Click here to open Exonprimer with this transcript

To design primers for a non-coding sequence, zoom to a region of interest and select from the drop-down menu: View > In External Tools > Primer3


-  MalaCards Disease Associations
  MalaCards Gene Search: CLDN18
Diseases sorted by gene-association score: ulcerative colitis (4), mucinous ovarian cystadenoma (2), gastric cancer, somatic (1)

-  Comparative Toxicogenomics Database (CTD)
  The following chemicals interact with this gene           more ... click here to view the complete list

-  RNA-Seq Expression Data from GTEx (53 Tissues, 570 Donors)
  Highest median expression: 256.69 RPKM in Stomach
Total median expression: 316.44 RPKM



View in GTEx track of Genome Browser    View at GTEx portal     View GTEx Body Map

+  Microarray Expression Data
 
Expression ratio colors:

GNF Expression Atlas 2 Data from U133A and GNF1H Chips

      
      
      
     
    
     
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-  mRNA Secondary Structure of 3' and 5' UTRs
 
RegionFold EnergyBasesEnergy/Base
Display As
5' UTR -19.1061-0.313 Picture PostScript Text
3' UTR -704.202508-0.281 Picture PostScript Text

The RNAfold program from the Vienna RNA Package is used to perform the secondary structure predictions and folding calculations. The estimated folding energy is in kcal/mol. The more negative the energy, the more secondary structure the RNA is likely to have.

-  Protein Domain and Structure Information
  InterPro Domains: Graphical view of domain structure
IPR006187 - Claudin
IPR003928 - Claudin18
IPR017974 - Claudin_CS
IPR004031 - PMP22/EMP/MP20/Claudin

Pfam Domains:
PF00822 - PMP-22/EMP/MP20/Claudin family

ModBase Predicted Comparative 3D Structure on P56856
FrontTopSide
The pictures above may be empty if there is no ModBase structure for the protein. The ModBase structure frequently covers just a fragment of the protein. You may be asked to log onto ModBase the first time you click on the pictures. It is simplest after logging in to just click on the picture again to get to the specific info on that model.

-  Orthologous Genes in Other Species
  Orthologies between human, mouse, and rat are computed by taking the best BLASTP hit, and filtering out non-syntenic hits. For more distant species reciprocal-best BLASTP hits are used. Note that the absence of an ortholog in the table below may reflect incomplete annotations in the other species rather than a true absence of the orthologous gene.
MouseRatZebrafishD. melanogasterC. elegansS. cerevisiae
Genome BrowserGenome BrowserNo orthologNo orthologNo orthologNo ortholog
Gene Details     
Gene Sorter     
MGIRGD    
Protein SequenceProtein Sequence    
AlignmentAlignment    

-  Gene Ontology (GO) Annotations with Structured Vocabulary
  Molecular Function:
GO:0005198 structural molecule activity
GO:0042802 identical protein binding

Biological Process:
GO:0016338 calcium-independent cell-cell adhesion via plasma membrane cell-adhesion molecules
GO:0045471 response to ethanol
GO:0045779 negative regulation of bone resorption
GO:0048565 digestive tract development
GO:0071847 TNFSF11-mediated signaling pathway
GO:1900181 negative regulation of protein localization to nucleus
GO:2001205 negative regulation of osteoclast development

Cellular Component:
GO:0005886 plasma membrane
GO:0005923 bicellular tight junction
GO:0016020 membrane
GO:0016021 integral component of membrane
GO:0030054 cell junction


-  Descriptions from all associated GenBank mRNAs
  AK098474 - Homo sapiens cDNA FLJ25608 fis, clone STM00359, highly similar to CLAUDIN-18.
AF349452 - Homo sapiens claudin-18A2.1 mRNA, complete cds, alternatively spliced.
AK298103 - Homo sapiens cDNA FLJ55115 complete cds, highly similar to Claudin-18.
AY358479 - Homo sapiens clone DNA73734 CLDN18 (UNQ778) mRNA, complete cds.
BC142708 - Homo sapiens claudin 18, mRNA (cDNA clone MGC:165050 IMAGE:40148818), complete cds.
BC146668 - Homo sapiens claudin 18, mRNA (cDNA clone MGC:164931 IMAGE:40148169), complete cds.
BC063845 - Homo sapiens claudin 18, mRNA (cDNA clone IMAGE:6177081), partial cds.
AF221069 - Homo sapiens Claudin-18 mRNA, complete cds.
KJ893851 - Synthetic construct Homo sapiens clone ccsbBroadEn_03245 CLDN18 gene, encodes complete protein.
AY102073 - Homo sapiens surfactant associated protein J mRNA, partial sequence.

-  Biochemical and Signaling Pathways
  KEGG - Kyoto Encyclopedia of Genes and Genomes
hsa04514 - Cell adhesion molecules (CAMs)
hsa04530 - Tight junction
hsa04670 - Leukocyte transendothelial migration

Reactome (by CSHL, EBI, and GO)

Protein P56856 (Reactome details) participates in the following event(s):

R-HSA-420019 Claudins create paired strands through homophilic and heterophilic cis and trans interactions
R-HSA-420029 Tight junction interactions
R-HSA-421270 Cell-cell junction organization
R-HSA-446728 Cell junction organization
R-HSA-1500931 Cell-Cell communication

-  Other Names for This Gene
  Alternate Gene Symbols: A5PL21, CLD18_HUMAN, ENST00000183605.1, ENST00000183605.2, ENST00000183605.3, ENST00000183605.4, ENST00000183605.5, ENST00000183605.6, ENST00000183605.7, ENST00000183605.8, ENST00000183605.9, NM_016369, P56856, Q96PH4, uc003erp.1, uc003erp.2, uc003erp.3, UNQ778/PRO1572
UCSC ID: ENST00000183605.10
RefSeq Accession: NM_016369.4
Protein: P56856 (aka CLD18_HUMAN or CLDI_HUMAN)
CCDS: CCDS3095.1

-  Methods, Credits, and Use Restrictions
  Click here for details on how this gene model was made and data restrictions if any.