Heterodimer of a type I and a type II keratin. KRT6 isomers associate with KRT16 and/or KRT17. Constitutively expressed in distinct types of epithelia such as those in oral mucosa, esophagus, papillae of tongue and hair follicle outer root sheath. The disease is caused by variants affecting the gene represented in this entry. There are at least six isoforms of human type II keratin-6 (K6). There are two types of cytoskeletal and microfibrillar keratin, I (acidic) and II (neutral to basic) (40-55 and 56-70 kDa, respectively). Belongs to the intermediate filament family.