epiplakins

Epiplakin is a member of the plakin family of cytoskeletal linker proteins. In humans, it is encoded by the EPPK1 gene. Epiplakin is a very large cytoplasmic protein that is broadly expressed in epithelial tissues, where it associates with the keratin intermediate filament network.

Structurally, epiplakin is characterized by a long array of plakin repeat domains and lacks many of the modular domains found in other plakins, such as distinct actin- or intermediate filament-binding modules with defined regulatory regions. The protein does not contain transmembrane segments and is mainly localized in the cytoplasm, where it is thought to interact with keratin filaments rather than with membranes.

In cells, epiplakin binds to keratin intermediate filaments and is believed to contribute to the stabilization and proper organization of the keratin network. This association supports the mechanical resilience of epithelial cells and may participate in cytoskeletal remodeling during stress, injury, or wound healing. Epiplakin expression can be modulated by cellular stress and signaling pathways that regulate the cytoskeleton.

Research on epiplakin has included cell culture studies and animal models, aimed at understanding its role in keratin network organization and epithelial integrity. While altered expression has been observed in certain skin conditions and some cancers, clear causative links to specific human diseases have not been firmly established. Epiplakin remains of interest as a marker and potential regulator of epithelial cytoskeletal architecture.