Type I keratin

Type I keratins (or Type I cytokeratins) constitutes the Type I intermediate filaments (IFs) of the intracytoplasmatic cytoskeleton, which is present in all mammalian epithelial cells. Most of the type I cytokeratins consist of acidic, low molecular weight proteins which in vivo are arranged in pairs of heterotypic Type I and Type II keratin chains, coexpressed during differentiation of simple and stratified epithelial tissues.

Type I cytokeratins are encoded on chromosome 17q and encompasses: CK9, CK10, CK11, CK12, CK13, CK14, CK15, CK16, CK17, CK18, CK19 and CK20. Their molecular weight ranges from 40 kDa (CK19) to 64 kDa (CK9).