Talk:Lecture - Integumentary Development
From Embryology
Lecture History
Keratins
- Keratins are the major structural proteins of the vertebrate epidermis and its appendages, constituting up to 85% of a fully differentiated keratinocyte.
- Together with actin microfilaments and microtubules, keratin filaments make up the cytoskeletons of vertebrate epithelial cells.
- Traced as far back in the evolutionary kingdom as mollusks, keratins belong to the superfamily of intermediate filament (IF) proteins that form alpha-helical coiled-coil dimers which associate laterally and end-to-end to form 10-nm diameter filaments.
- The evolutionary transition between organisms bearing an exoskeleton and those with an endoskeleton seemed to cause considerable change in keratin.
- Keratins expanded from a single gene to a multigene family. Of the approximately 60 IF genes in the human genome, half encode keratins, and at least 18 of these are expressed in skin.
- Vertebrate keratins are subdivided into two sequence types (I and II) that are typically coexpressed as specific pairs with complex expression patterns.
- The filament-forming capacity of a pair is dependent upon its intrinsic ability to self-assemble into coiled-coil heterodimers, a feature not required of the invertebrate keratins (Weber et al 1988).
- Approximately 20,000 heterodimers of type I and type II keratins assemble into an IF. Mutations that perturb keratin filament assembly in vitro can cause blistering human skin disorders in vivo.
(text from Review Article)
