[8][9] This protein is involved in several diseases including epidermolysis bullosa simplex and breast and lung cancers.

[12] Lying on either side of the central rod are variable, non-helical head and tail regions which protrude from the IF surface and provide specificity to different IF polypeptides.

[8][14] Keratin 5 (and K14) are expressed primarily in basal keratinocytes in the epidermis, specifically in the stratified epithelium lining the skin and digestive tract.

[9][14][15] K5/K14 keratin pairs are able to undergo extensive bundling due to the non-helical tail of K15 acting as a weak cross-linker at the intermediate filament surface.

Their mechanism of action is dominant negative interference, with the mutated keratin proteins interfering with the structure and integrity of the cytoskeleton.

Since the “hotspot” regions contain the initiation and termination sequences of the alpha-helical rod, mutations at these spots usually have a larger effect on helix stabilization and heterodimer formation.

Due to the fact that K5 expression is only seen in basal cells, it serves as an important biomarker for screening patients with basal-like breast cancers to ensure that they are not receiving ineffective treatment.