Keratin 6A 916285 224688641 2008-07-09T23:50:15Z Plasticup 2666389 clean up using [[Project:AutoWikiBrowser|AWB]] {{protein | Name = keratin 6A | caption = | image = | width = | HGNCid = 6443 | Symbol = KRT6A | AltSymbols = | EntrezGene = 3853 | OMIM = 148041 | RefSeq = NM_005554 | UniProt = P02538 | PDB = | ECnumber = | Chromosome = 12 | Arm = q | Band = 12 | LocusSupplementaryData = -q21 }} == Keratins == [[Keratins]] are the [[intermediate filament]] proteins that form a dense meshwork of filaments throughout the [[cytoplasm]] of [[epithelial]] cells. Keratins form hetero[[polymers]] consisting of a type I and a type II keratin. Keratins are generally expressed in particular pairs of type I and type II keratin proteins in a [[Tissue (biology)|tissue]]-specific and [[cellular differentiation]]-specific manner. The keratin proteins of epithelial tissues are commonly known as "keratins" or are sometimes referred to as "epithelial keratins" or "cytokeratins". The specialized keratins of [[hair]] and [[nail (anatomy)|nail]] are known as "hard keratins" or "[[trichocyte]] keratins". Trichocytes are the specialized epithelial cells from which hair and nail are composed. Trichocyte keratins are similar in their gene and protein structure to keratins except that they are especially rich in the [[sulfur]]-containing [[amino acid]] cysteine, which facilitates chemical cross-linking of the assembled hard keratins to form a more structurally resilient material. Both epithelial keratins and hard keratins can be further subdivided into type I (acidic) keratins and type II (neutral-basic) keratins. The genes for the type I keratins are located in a gene cluster on human [[chromosome]] 17q, whereas the genes for type II keratins are located in a cluster on human [[chromosome]] 12q (the exception being K18, a type I keratin located in the type II gene cluster). == Keratin 6A == '''Keratin 6A''' (protein name K6A; gene name ''KRT6A''), is a type II cyto[[keratin]], one of a number of [[isoform]]s of [[keratin 6]] encoded by separate genes located within the type II keratin gene cluster on human [[chromosome]] 12q. It is found with [[keratin 16]] and/or [[keratin 17]] in the palm and sole epidermis, the epithelial cells of the nail bed, the [[filiform papillae]] of the [[tongue]], the [[epithelial]] lining of oral [[mucosa]] and [[esophagus]], as well as the [[hair follicle]]s. This keratin 6 isoform is thought to be the most abundant of the K6 isoforms. The ''KRT6A'' gene consists of 9 [[exons]] separated by 8 [[introns]] and is located in the type II keratin gene cluster on human ''chromosome'' 12q. [[Keratin 6B]] and [[keratin 6C]] are encoded by the neighbouring genes, which are identical in [[intron]]-[[exon]] organization to ''KRT6A'' and are more than 99% identical in their [[DNA]] coding sequences. == Genetic disorders == Mutations in the genes expressing this protein have been associated with the PC1 variant of [[pachyonychia congenita]], an inherited disorder of the [[epithelial]] tissues in which keratin 6A is expressed, particularly leading to structural abnormalities of the nails, the [[Epidermis (skin)|epidermis]] of the palms and soles, and oral [[epithelia]] <ref>McLean WHI et al. (1995) Keratin 16 and keratin 17 mutations cause pachyonychia congenita. Nature Genetics 9:273-278. Abstract available here[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=7539673&query_hl=8&itool=pubmed_docsum].</ref><ref>Bowden PE et al. (1995) Mutation of a type II keratin gene (K6a) in pachyonychia congenita. Nature Genetics 10:363-365. Abstract available here[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=7545493&query_hl=10&itool=pubmed_docsum].</ref><ref>Smith FJD et al. (1998) A mutation in human keratin K6b produces a phenocopy of the K17 disorder pachyonychia congenita type 2. Human Molecular Genetics 7:1143-1148. Abstract available here[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=9618173&query_hl=12&itool=pubmed_docsum].</ref>. ==References== {{reflist}} {{Fibrous proteins}} [[Category:Keratins]]