Type II keratin

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KRT1 Structure with type 2 highlighted

Type II Keratins are a group of keratins that, along with Type I keratins, form the intermediate filaments in epithelial cells. These proteins are essential for the structural integrity and function of epithelial tissues. Type II keratins are characterized by their basic to neutral isoelectric points, which differentiate them from the acidic Type I keratins. Together, Type I and Type II keratins assemble into heterodimers, which then form tetramers and subsequently the intermediate filament network that provides mechanical support and resilience to cells and tissues.

Structure and Function

Type II keratins are encoded by a cluster of genes located on chromosome 12 in humans. These proteins typically range from 53 to 67 kDa in size. The structure of keratins includes a central rod domain flanked by non-helical head and tail domains. The rod domain is responsible for the formation of the coiled-coil dimers, a fundamental step in the assembly of the intermediate filament network.

The expression of Type II keratins is tightly regulated and tissue-specific, often paired with a specific Type I keratin to form the appropriate intermediate filament for that cell type. For example, keratin 5 (a Type II keratin) pairs with keratin 14 (a Type I keratin) in basal cells of the epidermis, contributing to the mechanical strength of the skin.

Clinical Significance

Mutations in Type II keratin genes can lead to a variety of genetic disorders, primarily affecting the skin and its appendages. These conditions are generally termed keratinopathies and include diseases such as epidermolysis bullosa simplex, keratoderma, and epidermolytic hyperkeratosis. These disorders are characterized by fragility of the skin and mucous membranes, leading to blistering and other skin abnormalities in response to minor mechanical trauma.

Research and Applications

Research into Type II keratins has provided insights into the fundamental processes of cell structure and cohesion. Beyond their structural roles, studies have shown that keratins are involved in cell signaling, migration, and wound healing. Understanding the complex roles of keratins in health and disease continues to be an active area of research, with potential applications in regenerative medicine and the development of novel therapies for keratin-related disorders.

See Also

• Intermediate filament
• Epithelial cell
• Genetic disorder
• Keratinopathy
• Chromosome 12

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