In the wool cortex, wool keratin intermediate filaments are embedded in an interfilamentous matrix, consisting of hair keratin-associated proteins (KRTAP), which are essential for the formation of a rigid and resistant wool shaft through their extensive disulfide bond cross-linking with abundant cysteine residues of wool keratins. The matrix proteins include the high-sulfur and high-glycine-tyrosine keratins. Interacts with wool keratins. Wool. Belongs to the KRTAP type 8 family.