Based on limited published evidence, KRTAP20-1 encodes a keratin-associated protein (KAP) that functions in hair shaft structure. According to UniProt annotations, KRTAP20-1 is embedded in the interfilamentary matrix of hair cortex, contributing to hair rigidity and resistance through disulfide bond cross-linking with hair keratins [UniProt]. In sheep, KRTAP20-1 variants associate with wool traits including fiber diameter and fleece weight 1. The protein localizes to the cytosol [GO]. Notably, unlike most KAPs, ovine KRTAP20-1 variants show functional effects independent of nearby KRTAP genes, suggesting distinct structural roles in fiber formation 1.