KRTAP2-2 Gene: Keratin Associated Protein 2-2 | Function, Location, and Disease

KRTAP2-2 (Keratin Associated Protein 2-2) is a protein-coding gene located on chromosome 17q21.2. It encodes a member of the high-sulfur keratin-associated protein (KAP) family, which are structural components of hair and nail matrix. KRTAP2-2 is specifically expressed in the hair follicle cortex and contributes to the mechanical strength and rigidity of hair shafts through disulfide cross-linking with keratin intermediate filaments. The gene is part of a cluster of KAP genes on chromosome 17, and its protein product is characterized by a high cysteine content. Mutations or altered expression of KRTAP2-2 may influence hair shaft integrity and have been studied in the context of hair disorders, though no definitive disease-causing mutations have been established to date.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Keratinization (Reactome: R-HSA-6805567)

• Formation of the cornified envelope (Reactome: R-HSA-6809371)

The KRTAP2-2 protein is a small, cysteine-rich protein (approximately 10 kDa) that belongs to the high-sulfur keratin-associated protein family. It is synthesized in the hair follicle cortex and cross-links with keratin intermediate filaments via disulfide bonds, contributing to the mechanical rigidity and chemical resistance of hair. The protein contains a characteristic repeat motif rich in cysteine and proline residues. Its expression is tightly regulated during hair cycle, and it is not expressed in other tissues at significant levels. Structural studies suggest that KRTAP2-2 forms a matrix around keratin filaments, essential for hair shaft integrity.