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Protein

Keratin, type I cytoskeletal 18

Gene

Krt18

Organism
Rattus norvegicus (Rat)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

When phosphorylated, plays a role in filament reorganization. Involved in the delivery of mutated CFTR to the plasma membrane. Together with KRT8, is involved in interleukin-6 (IL-6)-mediated barrier protection (By similarity). Involved in the uptake of thrombin-antithrombin complexes by hepatic cells.By similarity1 Publication

Sites

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Sitei264 – 2641StutterSequence analysis
Sitei324 – 3241StutterSequence analysis

GO - Molecular functioni

GO - Biological processi

Complete GO annotation...

Names & Taxonomyi

Protein namesi
Recommended name:
Keratin, type I cytoskeletal 18
Alternative name(s):
Cytokeratin-18
Short name:
CK-18
Keratin-18
Short name:
K18
Gene namesi
Name:Krt18By similarity
Synonyms:Krt1-18Imported
OrganismiRattus norvegicus (Rat)
Taxonomic identifieri10116 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresGliresRodentiaSciurognathiMuroideaMuridaeMurinaeRattus
Proteomesi
  • UP000002494 Componenti: Chromosome 7

Organism-specific databases

RGDi619935. Krt18.

Subcellular locationi

GO - Cellular componenti

Complete GO annotation...

Keywords - Cellular componenti

Cytoplasm, Intermediate filament, Keratin, Nucleus

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Initiator methionineiRemovedBy similarity
Chaini2 – 423422Keratin, type I cytoskeletal 18PRO_0000063668Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Modified residuei2 – 21N-acetylserineBy similarity
Modified residuei7 – 71PhosphoserineBy similarity
Modified residuei11 – 111PhosphoserineBy similarity
Modified residuei16 – 161PhosphoserineBy similarity
Modified residuei19 – 191PhosphoserineCombined sources
Modified residuei31 – 311Phosphoserine; alternateCombined sources
Glycosylationi31 – 311O-linked (GlcNAc); alternateBy similarity
Modified residuei32 – 321Phosphoserine; alternateBy similarity
Glycosylationi32 – 321O-linked (GlcNAc); alternateBy similarity
Modified residuei35 – 351PhosphoserineCombined sources
Modified residuei37 – 371PhosphotyrosineBy similarity
Modified residuei43 – 431PhosphoserineBy similarity
Modified residuei50 – 501Phosphoserine; alternateBy similarity
Glycosylationi50 – 501O-linked (GlcNAc); alternateBy similarity
Modified residuei52 – 521Phosphoserine; by MAPKAPK2 and MAPKAPK3By similarity
Modified residuei57 – 571PhosphoserineCombined sources
Modified residuei60 – 601PhosphoserineBy similarity
Modified residuei85 – 851PhosphoserineBy similarity
Modified residuei124 – 1241N6-acetyllysineBy similarity
Modified residuei137 – 1371PhosphoserineBy similarity
Modified residuei170 – 1701PhosphoserineBy similarity
Modified residuei295 – 2951PhosphothreonineBy similarity
Modified residuei384 – 3841PhosphoserineBy similarity
Modified residuei391 – 3911PhosphoserineBy similarity
Modified residuei392 – 3921PhosphoserineBy similarity
Modified residuei394 – 3941PhosphoserineBy similarity
Modified residuei397 – 3971PhosphothreonineBy similarity

Post-translational modificationi

Phosphorylation increases by IL-6.By similarity
Proteolytically cleaved by caspases during epithelial cell apoptosis. Cleavage occurs at Asp-231 by either caspase-3, caspase-6 or caspase-7 (By similarity).By similarity
Dephosphorylated by ethanol.1 Publication
O-GlcNAcylation increases solubility, and decreases stability by inducing proteasomal degradation.By similarity

Sites

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Sitei231 – 2322Cleavage; by caspase-3, caspase-6 or caspase-7By similarity

Keywords - PTMi

Acetylation, Glycoprotein, Phosphoprotein

Proteomic databases

PaxDbiQ5BJY9.
PRIDEiQ5BJY9.

PTM databases

iPTMnetiQ5BJY9.
PhosphoSiteiQ5BJY9.

Expressioni

Tissue specificityi

Expressed on the plasma membrane of hepatocytes and in the narrow apical portions of supporting cells in the vomeronasal sensory epithelium. Detected in the type III alveolar cells of the lung, in the proliferative crypt epithelium of the small intestine and in the older intragemmal cells of the tongue.7 Publications

Developmental stagei

Expression first detected in the male gonad at 13.5 dpc, at the onset of testicular differentiation, and at 17 dpc in cell aggregates of the early ovary; then only in some cord cells of the older ovary. Expressed in fetal lung epithelium at 20 dpc. Detected at 13 dpc, sparsely distributed throughout the cytoplasm in the single layer of periderm cells covering the dorsal epithelium of the fetal tongue. Expression increases in the lingual periderm cells at 17 dpc and then disappears at 19 dpc coinciding with the disappearance of the periderm cells at the onset of squamous stratification of the lingual epithelium. Expressed at day 2-3 postnatally in older, elongated taste bud cells and at day 5, uniformly distributed throughout the epithelium of villi, intervillus epithelium and developing crypt buds of the small intestine.7 Publications

Inductioni

By IL-6 (By similarity). By fibronectin.By similarity1 Publication

Gene expression databases

GenevisibleiQ5BJY9. RN.

Interactioni

Subunit structurei

Heterotetramer of two type I and two type II keratins. KRT18 associates with KRT8. Interacts with PNN, HCV core protein and mutated CFTR. Interacts with YWHAE, YWHAH and YWHAZ only when phosphorylated. Interacts with DNAJB6, TCHP and TRADD (By similarity). Interacts with the thrombin-antithrombin complex. Interacts with FAM83H (By similarity).By similarity1 Publication

Protein-protein interaction databases

STRINGi10116.ENSRNOP00000067234.

Structurei

3D structure databases

ProteinModelPortaliQ5BJY9.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Region

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Regioni2 – 7170HeadSequence analysisAdd
BLAST
Regioni62 – 366305Necessary for interaction with PNNBy similarityAdd
BLAST
Regioni69 – 12153Interaction with TRADDBy similarityAdd
BLAST
Regioni72 – 380309RodSequence analysisAdd
BLAST
Regioni72 – 10736Coil 1ASequence analysisAdd
BLAST
Regioni108 – 12518Linker 1Sequence analysisAdd
BLAST
Regioni126 – 21792Coil 1BSequence analysisAdd
BLAST
Regioni218 – 24124Linker 12Sequence analysisAdd
BLAST
Regioni236 – 384149Interaction with DNAJB6By similarityAdd
BLAST
Regioni242 – 380139Coil 2Sequence analysisAdd
BLAST
Regioni381 – 42343TailSequence analysisAdd
BLAST

Sequence similaritiesi

Belongs to the intermediate filament family.Sequence analysis

Keywords - Domaini

Coiled coil

Phylogenomic databases

eggNOGiENOG410IEYR. Eukaryota.
ENOG4111DJ8. LUCA.
GeneTreeiENSGT00760000119046.
HOGENOMiHOG000230975.
HOVERGENiHBG013015.
InParanoidiQ5BJY9.
KOiK07604.
OMAiRAKYEKM.
OrthoDBiEOG7V1FR3.
PhylomeDBiQ5BJY9.

Family and domain databases

InterProiIPR001664. IF.
IPR018039. Intermediate_filament_CS.
IPR027695. Keratin-18.
IPR002957. Keratin_I.
[Graphical view]
PANTHERiPTHR23239. PTHR23239. 1 hit.
PTHR23239:SF35. PTHR23239:SF35. 1 hit.
PfamiPF00038. Filament. 1 hit.
[Graphical view]
PRINTSiPR01248. TYPE1KERATIN.
SMARTiSM01391. Filament. 1 hit.
[Graphical view]
PROSITEiPS00226. IF. 1 hit.
[Graphical view]

Sequencei

Sequence statusi: Complete.

Sequence processingi: The displayed sequence is further processed into a mature form.

Q5BJY9-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MSFTTRSTTF STNYRSLGSV RTPSQRVRPA SSAASVYAGA GGSGSRISVS
60 70 80 90 100
RSVWGGSVGS AGLAGMGGVQ TEKETMQDLN DRLASYLDKV KNLETENRRL
110 120 130 140 150
ESKIREYLEK RGPQGVRDWG HYFKTIEDLR AQIFANSVDN ARIVLQIDNA
160 170 180 190 200
RLAADDFRVK YETELAMRQS VESDIHGLRK VVDDTNITRL QLETEIEALK
210 220 230 240 250
EELLFMKKNH EEEVQGLEAQ IASSGLTVEV DAPKSQDLSK IMADIRAQYE
260 270 280 290 300
QLAQKNREEL DKYWSQQIEE STTVVTTKSA EIRDAETTLL ELRRTLQTLE
310 320 330 340 350
IDLDSMKNQN INLENNLGEV EARYRVQMEQ LNGVLLHLES ELAQTRAEGQ
360 370 380 390 400
RQTQEYEALL NIKVKLEAEI ATYRRLLEDG DDFSLNDALD SSNSMQTVQR
410 420
TTTRKVVDGK VVSETNDTRV LRH
Length:423
Mass (Da):47,761
Last modified:January 23, 2007 - v3
Checksum:i793F0BAA275CCA4E
GO

Experimental Info

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Sequence conflicti125 – 1251T → I in CAA57204 (PubMed:8541209).Curated

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
BC091275 mRNA. Translation: AAH91275.1.
X81448 mRNA. Translation: CAA57204.1.
RefSeqiNP_446428.1. NM_053976.1.
UniGeneiRn.103924.

Genome annotation databases

EnsembliENSRNOT00000073951; ENSRNOP00000067234; ENSRNOG00000047393.
GeneIDi294853.
KEGGirno:294853.

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
BC091275 mRNA. Translation: AAH91275.1.
X81448 mRNA. Translation: CAA57204.1.
RefSeqiNP_446428.1. NM_053976.1.
UniGeneiRn.103924.

3D structure databases

ProteinModelPortaliQ5BJY9.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

STRINGi10116.ENSRNOP00000067234.

PTM databases

iPTMnetiQ5BJY9.
PhosphoSiteiQ5BJY9.

Proteomic databases

PaxDbiQ5BJY9.
PRIDEiQ5BJY9.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENSRNOT00000073951; ENSRNOP00000067234; ENSRNOG00000047393.
GeneIDi294853.
KEGGirno:294853.

Organism-specific databases

CTDi3875.
RGDi619935. Krt18.

Phylogenomic databases

eggNOGiENOG410IEYR. Eukaryota.
ENOG4111DJ8. LUCA.
GeneTreeiENSGT00760000119046.
HOGENOMiHOG000230975.
HOVERGENiHBG013015.
InParanoidiQ5BJY9.
KOiK07604.
OMAiRAKYEKM.
OrthoDBiEOG7V1FR3.
PhylomeDBiQ5BJY9.

Miscellaneous databases

PROiQ5BJY9.

Gene expression databases

GenevisibleiQ5BJY9. RN.

Family and domain databases

InterProiIPR001664. IF.
IPR018039. Intermediate_filament_CS.
IPR027695. Keratin-18.
IPR002957. Keratin_I.
[Graphical view]
PANTHERiPTHR23239. PTHR23239. 1 hit.
PTHR23239:SF35. PTHR23239:SF35. 1 hit.
PfamiPF00038. Filament. 1 hit.
[Graphical view]
PRINTSiPR01248. TYPE1KERATIN.
SMARTiSM01391. Filament. 1 hit.
[Graphical view]
PROSITEiPS00226. IF. 1 hit.
[Graphical view]
ProtoNetiSearch...

Publicationsi

« Hide 'large scale' publications
  1. "The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)."
    The MGC Project Team
    Genome Res. 14:2121-2127(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
    Tissue: ThymusImported.
  2. "Switch in the expression of the K19/K18 keratin genes as a very early evidence of testicular differentiation in the rat."
    Fridmacher V., le Bert M., Guillou F., Magre S.
    Mech. Dev. 52:199-207(1995) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] OF 124-270, DEVELOPMENTAL STAGE.
    Strain: WistarImported.
    Tissue: Fetal gonad1 Publication.
  3. "Proteome analysis of a rat liver nuclear insoluble protein fraction and localization of a novel protein, ISP36, to compartments in the interchromatin space."
    Segawa M., Niino K., Mineki R., Kaga N., Murayama K., Sugimoto K., Watanabe Y., Furukawa K., Horigome T.
    FEBS J. 272:4327-4338(2005) [PubMed] [Europe PMC] [Abstract]
    Cited for: PROTEIN SEQUENCE OF 131-140, SUBCELLULAR LOCATION.
    Tissue: Liver1 Publication.
  4. "Intermediate filament proteins and epithelial differentiation in the embryonic ovary of the rat."
    Frojdman K., Paranko J., Virtanen I., Pelliniemi L.J.
    Differentiation 55:47-55(1993) [PubMed] [Europe PMC] [Abstract]
    Cited for: DEVELOPMENTAL STAGE.
  5. "Cytokeratin expression in epithelial cells isolated from the crypt and villus regions of the rodent small intestine."
    Flint N., Pemberton P.W., Lobley R.W., Evans G.S.
    Epithelial Cell Biol. 3:16-23(1994) [PubMed] [Europe PMC] [Abstract]
    Cited for: TISSUE SPECIFICITY, DEVELOPMENTAL STAGE.
  6. "Colocalization of cytokeratin 18 and villin in type III alveolar cells (brush cells) of the rat lung."
    Kasper M., Hofer D., Woodcock-Mitchell J., Migheli A., Attanasio A., Rudolf T., Muller M., Drenckhahn D.
    Histochemistry 101:57-62(1994) [PubMed] [Europe PMC] [Abstract]
    Cited for: TISSUE SPECIFICITY.
  7. "Keratin 18 is associated with a subset of older taste cells in the rat."
    Zhang C., Cotter M., Lawton A., Oakley B., Wong L., Zeng Q.
    Differentiation 59:155-162(1995) [PubMed] [Europe PMC] [Abstract]
    Cited for: DEVELOPMENTAL STAGE.
  8. "Glycoconjugates and keratin 18 define subsets of taste cells."
    Zeng Q., Lawton A., Oakley B.
    Histochem. J. 27:997-1006(1995) [PubMed] [Europe PMC] [Abstract]
    Cited for: TISSUE SPECIFICITY, DEVELOPMENTAL STAGE.
  9. "Site-specificity of ethanol-induced dephosphorylation of rat hepatocyte keratins 8 and 18: a 31P NMR study."
    Eckert B.S., Yeagle P.L.
    Cell Motil. Cytoskeleton 33:30-37(1996) [PubMed] [Europe PMC] [Abstract]
    Cited for: DEPHOSPHORYLATION BY ETHANOL.
  10. "Cytokeratin 18 is expressed on the hepatocyte plasma membrane surface and interacts with thrombin-antithrombin complexes."
    Wells M.J., Hatton M.W., Hewlett B., Podor T.J., Sheffield W.P., Blajchman M.A.
    J. Biol. Chem. 272:28574-28581(1997) [PubMed] [Europe PMC] [Abstract]
    Cited for: FUNCTION, TISSUE SPECIFICITY, INTERACTION WITH THROMBIN-ANTITHROMBIN COMPLEX.
  11. "Fibronectin regulates morphology, cell organization and gene expression of rat fetal hepatocytes in primary culture."
    Sanchez A., Alvarez A.M., Pagan R., Roncero C., Vilaro S., Benito M., Fabregat I.
    J. Hepatol. 32:242-250(2000) [PubMed] [Europe PMC] [Abstract]
    Cited for: TISSUE SPECIFICITY, INDUCTION.
  12. "Identification of cytoskeletal markers for the different microvilli and cell types of the rat vomeronasal sensory epithelium."
    Hofer D., Shin D.W., Drenckhahn D.
    J. Neurocytol. 29:147-156(2000) [PubMed] [Europe PMC] [Abstract]
    Cited for: SUBCELLULAR LOCATION, TISSUE SPECIFICITY.
  13. "Foetal rat lung epithelial (FRLE) cells: partial characterisation and response to pneumotoxins."
    Ridd K., Alexander D.J., Reed C.J.
    Toxicol. in Vitro 18:79-88(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: TISSUE SPECIFICITY, DEVELOPMENTAL STAGE.
  14. "Expression of keratin 18 in the periderm cells of the lingual epithelium of fetal rats: visualization by fluorescence immunohistochemistry and differential interference contrast microscopy."
    Iwasaki S., Aoyagi H., Asami T.
    Odontology 94:64-68(2006) [PubMed] [Europe PMC] [Abstract]
    Cited for: SUBCELLULAR LOCATION, DEVELOPMENTAL STAGE.
  15. "Quantitative phosphoproteomics of vasopressin-sensitive renal cells: regulation of aquaporin-2 phosphorylation at two sites."
    Hoffert J.D., Pisitkun T., Wang G., Shen R.-F., Knepper M.A.
    Proc. Natl. Acad. Sci. U.S.A. 103:7159-7164(2006) [PubMed] [Europe PMC] [Abstract]
    Cited for: PHOSPHORYLATION [LARGE SCALE ANALYSIS] AT SER-19 AND SER-35, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
  16. "Quantitative maps of protein phosphorylation sites across 14 different rat organs and tissues."
    Lundby A., Secher A., Lage K., Nordsborg N.B., Dmytriyev A., Lundby C., Olsen J.V.
    Nat. Commun. 3:876-876(2012) [PubMed] [Europe PMC] [Abstract]
    Cited for: PHOSPHORYLATION [LARGE SCALE ANALYSIS] AT SER-31; SER-35 AND SER-57, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].

Entry informationi

Entry nameiK1C18_RAT
AccessioniPrimary (citable) accession number: Q5BJY9
Secondary accession number(s): Q63278
Entry historyi
Integrated into UniProtKB/Swiss-Prot: August 16, 2005
Last sequence update: January 23, 2007
Last modified: July 6, 2016
This is version 100 of the entry and version 3 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program

Miscellaneousi

Miscellaneous

There are two types of cytoskeletal and microfibrillar keratin: I (acidic; 40-55 kDa) and II (neutral to basic; 56-70 kDa).

Keywords - Technical termi

Complete proteome, Direct protein sequencing, Reference proteome

Documents

  1. SIMILARITY comments
    Index of protein domains and families

Similar proteinsi

Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into one UniRef entry.
90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.