Keratin 3 (K3) (K3)

Keratin 3 (K3), encoded by the KRT3 gene, is a type II cytokeratin protein specifically expressed in the corneal epithelium of the eye, where it pairs with keratin 12 to form heterotetrameric intermediate filaments that provide mechanical strength and resilience to this outermost corneal layer, acting as a barrier against foreign materials like dust and bacteria. These filaments create a robust network anchoring to cell junctions, distributing mechanical stress to maintain tissue integrity. Mutations in KRT3, particularly in the helix termination motif critical for filament assembly, disrupt this structure, leading to fragile epithelium and cyst formation characteristic of Meesmann corneal dystrophy, an inherited eye disorder causing irritation, photophobia, and vision issues. While cytokeratins broadly serve as diagnostic biomarkers in pathology for identifying epithelial cancers via immunohistochemistry, K3's role is confined to corneal-specific pathology rather than oncology or systemic diseases. No approved drugs directly target K3, reflecting its niche as a structural cytoskeletal component rather than a conventional therapeutic receptor, enzyme, or signaling molecule.

Other names

65 kDa cytokeratinCK-3CK3cytokeratin 3cytokeratin-3K2C3_HUMANkeratin 3 type IIkeratin type II cytoskeletal 3type-II keratin Kb3