Keratin 3

Keratin 3 is a type I intermediate filament (IF) protein. It is specifically expressed in the suprabasal layers of certain types of epithelial cells, primarily in the cornea and certain internal stratified epithelia. It always co-expresses and heterodimerizes with its type II partner, keratin 12, to form the keratin filaments responsible for maintaining the structural integrity and mechanical resilience of these tissues. Mutations in KRT3, the gene encoding keratin 3, are associated with Meesmann's corneal dystrophy (MECD), an autosomal dominant disease characterized by corneal epithelial fragility and the formation of small, clear cysts in the corneal epithelium. These mutations disrupt the normal formation of the keratin 3/keratin 12 network, leading to cellular dysfunction and the characteristic symptoms of MECD. The specific role of Keratin 3 is critical in corneal epithelial cells due to the unique mechanical stresses experienced by the cornea.