Epidermal keratin and epidermal prekeratin.

Abstract

PROGRESS in understanding keratinization of the epidermis has been hampered by the difficulty of preparing a reproducible keratinous protein from the epidermal tissue1,2. Several laboratories1–5 have obtained an alkali- or urea-extractable protein from human, mouse, and cow's snout epidermis which precipitates from solutions at pH 5.5. This protein is present in large amounts in fully keratinized human epidermal tissue (callus or stratum corneum)1,2 and is believed to represent epidermal “keratin”. Matoltsy6–8 has isolated and characterized a similar protein from cow's snout epidermis which is soluble in acetic acid. This protein is termed “prekeratin” by virtue of its ready solubility from whole epidermis which includes incompletely keratinized cells (full-thickness cow's snout epidermis). This report compares human callus keratin (protein precipitating at pH 5.5) with the prekeratin of Matoltsy. Their similarities heighten optimism concerning the definition of an epidermal keratin sub-unit.