Bidirectional Binding Property of High Glycine–Tyrosine Keratin-Associated Protein Contributes to the Mechanical Strength and Shape of Hair

The study hypothesized that high glycine-tyrosine keratin-associated proteins (HGT KAPs) contributed to hair's mechanical strength and shape by bridging the head domains of intermediate filaments (IFs) and binding to both IFs and the C-terminus of desmoplakin (DPCT). This was supported by protein interaction analyses, including Western blot, isothermal titration calorimetry (ITC), and circular dichroism (CD), which showed strong binding interactions between HGT KAPs and the head domain of K85, a trichocyte IF protein.