Keratin 8

Keratin, type II cytoskeletal 8 also known as cytokeratin-8 (CK-8) or keratin-8 (K8) is a keratin protein that is encoded in humans by the KRT8 gene. It is often paired with keratin 18.

KRT8
Identifiers
Aliases	KRT8, CARD2, CK-8, CK8, CYK8, K2C8, K8, KO, keratin 8
External IDs	OMIM: 148060; MGI: 96705; HomoloGene: 55643; GeneCards: KRT8; OMA:KRT8 - orthologs
Gene location (Human) Chr. Chromosome 12 (human)[1] Band 12q13.13 Start 52,897,187 bp[1] End 52,949,954 bp[1]
Gene location (Mouse) Chr. Chromosome 15 (mouse)[2] Band 15 F2|15 57.2 cM Start 101,905,133 bp[2] End 101,912,917 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in mucosa of transverse colon duodenum rectum placenta islet of Langerhans olfactory zone of nasal mucosa body of pancreas gallbladder epithelium of bronchus left lobe of thyroid gland Top expressed in ileum jejunum colon duodenum placenta stomach urinary bladder middle ear islet of Langerhans yolk sac More reference expression data BioGPS n/a
Gene ontology Molecular function protein-containing complex binding scaffold protein binding structural molecule activity protein binding Cellular component cytoplasm cell-cell junction nuclear matrix dystrophin-associated glycoprotein complex keratin filament nucleoplasm Z discdkac sarcolemma costamere extracellular exosome intermediate filament nucleus cell periphery cytosol apicolateral plasma membrane intermediate filament cytoskeleton Biological process extrinsic apoptotic signaling pathway response to hydrostatic pressure tumor necrosis factor-mediated signaling pathway response to other organism viral process cell differentiation involved in embryonic placenta development sarcomere organization hepatocyte apoptotic process keratinization cornification Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 3856 16691 Ensembl ENSG00000170421 ENSMUSG00000049382 UniProt P05787 P11679 RefSeq (mRNA) NM_001256282 NM_001256293 NM_002273 NM_031170 RefSeq (protein) NP_001243211 NP_001243222 NP_002264 NP_112447 Location (UCSC) Chr 12: 52.9 – 52.95 Mb Chr 15: 101.91 – 101.91 Mb PubMed search [3] [4]
Wikidata
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Utility as an immunohistochemical stain

Antibodies to CK8 (e.g. CAM 5.2) can be used to differentiate lobular carcinoma of the breast from ductal carcinoma of the breast.^[5] CAM 5.2, an antibody that reacts with an epitope found on both CK8 and CK18, is used in immunohistochemistry to demonstrate certain forms of cancer. In normal tissue, it reacts mainly with secretory epithelia, but not with squamous epithelium, such as that found in the skin, cervix, and esophagus. However, it also reacts with a range of malignant cells, including those derived from secretory epithelia, but also some squamous carcinomata, such as spindle cell carcinoma. It is considered useful in identifying microscopic metastases of breast carcinoma in lymph nodes, and in distinguishing Paget's disease from malignant melanoma. It also reacts with neuroendocrine tumors.^[6]

Keratin 8 is often used together with keratin 18 and keratin 19 to differentiate cells of epithelial origin from hematopoietic cells in tests that enumerate circulating tumor cells in blood.^[7]

Interactions

Keratin 8 has been shown to interact with MAPK14,^[8] Pinin^[9] and PPL.^[10]

Cytokeratin 8 staining in the human breast cancer cell line MCF-7

See also

• Immunohistochemistry