Cytokeratin

The term cytokeratin began to be used in the late 1970s, when the protein subunits of keratin intermediate filaments inside cells were first being identified and characterized.

The subsets of cytokeratins which an epithelial cell expresses depends mainly on the type of epithelium, the moment in the course of terminal differentiation and the stage of development.

Thus the study of cytokeratin expression by immunohistochemistry techniques is a tool of immense value widely used for tumor diagnosis and characterization in surgical pathology.

The subdomains V1 and V2 contain residues enriched by glycines and/or serines, the former providing the cytokeratin chain a strong insoluble character and facilitating the interaction with other molecules.

This association between the plasma membrane and the nuclear surface provides important implications for the organization of the cytoplasm and cellular communication mechanisms.

Apart from the relatively static functions provided in terms of supporting the nucleus and providing tensile strength to the cell, the cytokeratin networks undergo rapid phosphate exchanges mediated depolymerization, with important implications in the more dynamic cellular processes such as mitosis and post-mitotic period, cell movement and differentiation.

The intermediate filaments of the eukaryotic cytoskeleton, which the cytokeratins are one of its three components, have been probed to associate also with the ankyrin and spectrin complex protein network that underlies the cell membrane.