Keratin 1 (K1) (K1)

Keratin 1 (K1), also known as cytokeratin 1 or CK1, is a type II (basic/neutral) intermediate filament protein expressed primarily in the suprabasal layers of stratified keratinizing epithelia, such as the epidermis. It pairs with the type I keratin 10 (K10) to form heterodimers that assemble into filaments, providing mechanical strength, structural integrity, and resistance to physical stress by anchoring to desmosomes and hemidesmosomes. This network extends from the nucleus to the plasma membrane, supporting cell adhesion, tissue architecture, and adaptation to environmental forces, while also participating in dynamic processes like mitosis, differentiation, and signaling. In disease, altered K1 expression or mutations are linked to skin disorders involving defective cornification, and its tissue-specific profile serves as a key immunohistochemical biomarker for identifying epithelial tumor origins, particularly in squamous cell carcinomas where K1/K10 indicates differentiated areas. Though not a direct therapeutic target like receptors or enzymes, K1's role in epithelial homeostasis makes it valuable for pathology diagnostics rather than drug modulation, with no approved interacting drugs identified.

Other names

Cytokeratin 1CK1Keratin-1