Required for the formation of keratin intermediate filaments in the basal epidermis and maintenance of the skin barrier in response to mechanical stress (By similarity). Regulates the recruitment of Langerhans cells to the epidermis, potentially by modulation of the abundance of macrophage chemotactic cytokines, macrophage inflammatory cytokines and CTNND1 localization in keratinocytes (By similarity). Heterodimer of a type I and a type II keratin (PubMed:22705788, PubMed:31995743). Heterodimer with type I keratin KRT25 leading to the formation of keratin intermediate filament (KIF) network (PubMed:28899683). Forms a heterodimer (via 2B domains) with KRT14 (via 2B domains) (PubMed:24940650, PubMed:22705788, PubMed:31995743). Interacts with PLEC isoform 1C, when in a heterodimer with KRT14 (PubMed:24940650). Interacts with TCHP (PubMed:15731013). Interacts with EPPK1 (By similarity). Interacts with AMELX (By similarity). Expressed in corneal epithelium (at protein level). Phosphorylated by CDK1, AURKB and Rho-kinase, phosphorylation is regulated by the cell cycle (By similarity). Thr-24 phosphorylation, mediated by CDK1, peaks during prometaphase or metaphase cells with phosphorylated filamentous structures evident throughout the cytoplasm during early mitosis (By similarity). CDK1 phosphorylates Thr-24 in mitotic cells at the site of injury (By similarity). O-glycosylated. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. There are two types of cytoskeletal and microfibrillar keratin: I (acidic; 40-55 kDa) and II (neutral to basic; 56-70 kDa). Belongs to the intermediate filament family.