Quantifying cytoskeletal protein interactions with far Western blotting

The study of cytoskeletal proteins has been limited by some of their intrinsic properties, such as fixed intracellular localization and insolubility, which limit the implementation of many protein-protein interaction assays. Far Western blotting is a powerful biochemical technique used to detect and quantify protein-protein interactions on a membrane, addressing limitations in cytoskeletal research. This method combines traditional Western blotting with protein overlay assays to identify and characterize binding partners in complex samples. Here, we present a detailed protocol for the use of far Western blotting to probe keratin-keratin interactions, including instructions for protein sample preparation, electrophoretic separation, membrane transfer, protein labeling, buffer dilutions, and detection steps. We further extend the use of far Western blotting to compare relative binding and enhance assay sensitivity by incorporating a Western blot as a loading control. This approach enables the analysis of samples that are too dilute for reliable membrane staining. Key considerations for enhancing specificity and sensitivity are discussed, along with troubleshooting tips. This approach offers a versatile tool for studying protein interaction networks, providing valuable insights into cellular signaling and molecular mechanisms, and can be conducted in any laboratory capable of performing a Western blot.