Keratin is classified primarily based on its secondary structure and also by its expression patterns and location within the body.
Primary Classification: α-keratin and β-keratin
The most common classification divides keratin into two main types:
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α-keratin: This type is the prevalent form found in mammalian epidermal materials such as hair, wool, and horns. It's characterized by its α-helical structure.
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β-keratin: This type is primarily found in birds and reptiles, specifically in structures like feathers and scales. Its structure is dominated by β-sheets.
Other classifications exist, further refining the categorization of keratins:
Secondary Classification: Based on Expression and Location
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Epidermal Keratins: These are classified according to their reactivity with monoclonal antibodies, isoelectric point, and mode of expression within the epidermis. This involves a complex system of identifying various keratin subtypes based on their properties and cellular location.
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Keratin in Melanoma Classification: Research uses keratin expression patterns, along with immune and melanogenesis patterns, to classify node-positive melanomas into prognostic subgroups. This illustrates the application of keratin classification in disease prognosis.
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Intermediate Filament Proteins (IFPs): Keratins are classified as intermediate filament proteins, indicating their structural role in cells. Both α and β-keratin fall under this broader category.
Keratinases: Enzymes that Degrade Keratin
Keratinases are enzymes capable of breaking down keratin. Their classification is based on their enzymatic activity and the specific type of keratin they degrade. This highlights the broader biological context of keratin's role and the associated enzymes.
Understanding keratin classification is crucial in various fields, including materials science (exploring keratin-based materials), medicine (diagnosing and understanding diseases like melanoma), and biotechnology (developing keratin-degrading enzymes for industrial applications).
