Classification of Epidermal Keratins according to Their Immunoreactivity, Isoelectric Point, and Mode of Expression

• Published in: The Journal of cell biology 1984-04, Vol.98 (4), p.1388-1396
• Main Authors: Eichner, Riva, Bonitz, Paula, Sun, Tung-Tien
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Antibodies; Antibodies, Monoclonal; Antigen-Antibody Complex; Biological and medical sciences; Cells, Cultured; Cultured cells; Electrophoresis; Electrophoresis, Polyacrylamide Gel; Epidermal cells; Epidermal Growth Factor - pharmacology; Epidermis; Epithelial cells; Fundamental and applied biological sciences. Psychology; Gels; Holoproteins; Humans; Hydrocortisone - pharmacology; Hydrogen-Ion Concentration; Infant, Newborn; Keratinocytes; Keratins; Keratins - immunology; Keratins - isolation & purification; Male; Molecular Weight; Monoclonal antibodies; Other proteins; Proteins; Skin - drug effects; Skin Physiological Phenomena; Vitamin A - pharmacology
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.98.4.1388

Human epidermal keratinocytes express under various growth conditions a total of at least nine keratins that can be divided into two subfamilies. Subfamily A comprises 40-, 46-, 48-, 50-/50′-, and 56.5-kilodalton (kd) keratins which are relatively acidic (pl 6) and are recognized by AE3 monoclonal antibody. Within each keratin subfamily, there is a constant member (50-/50′ - and 58-kd keratins of the subfamilies A and B, respectively) that is always expressed. The other seven keratins of both subfamilies are variable members whose expression depends upon the cellular differentiated state, which is in turn modulated by the growth environment. The 56.5-kd keratin (subfamily A) and the 65-67-kd keratins (subfamily B) are coordinately expressed during keratinization. In contrast, the 40-, 46-, and 48-kd keratins (subfamily A) and the 52- and 56-kd keratins (subfamily B) are characteristic of cultured epidermal cells forming nonkeratinized colonies. These results demonstrate that human epidermal keratins can be classified according to their reactivity with monoclonal antikeratin antibodies, isoelectric point, and mode of expression. The classification of keratins into various subgroups may have important implications for the mechanisms of epidermal differentiation, the evolution of keratin heterogeneity, and the use of keratin markers for tumor diagnosis.