Chapter 3: Expression and Modification of Keratins During Terminal Differentiation of Mammalian Epidermis

This chapter reviewed studies on keratin expression and modification during epidermal differentiation, highlighting two key processes: differentiation-related proteolysis and post-translational phosphorylation of keratins. It was noted that keratins, major phosphoproteins in keratinocytes, are not uniformly synthesized across the epidermis but are expressed sequentially, with variations depending on anatomical site. The chapter also discussed differences in keratin expression between cultured keratinocytes and in vivo conditions, suggesting these differences reflect changes in keratin gene expression control. Preliminary data on hair and nail keratins, referred to as "hard" keratins, were also presented.