Related Experiment Video
Updated: Apr 11, 2026

Generation of a Three-dimensional Full Thickness Skin Equivalent and Automated Wounding
Published on: February 26, 2015
The cornified envelope of terminally differentiated human epidermal keratinocytes consists of cross-linked protein
Abstract:
A small proportion of the protein of stratum corneum of human epidermal callus is insoluble even when boiled in solutions containing sodium dodecylsulfate and a reducing agent. This protein is present in the cornified envelope, a structure located beneath the plasma membrane. When cornified envelopes were dissolved by exhaustive proteolytic digestion and the products analyzed by chromatography, approximately 18% of the total lysine residues were found as the cross-linking dipeptide epsilon-(gamma-glutamyl) lysine. Labeled cornified envelope protein was synthesized by human epidermal keratinocytes allowed to differentiate terminally in culture. The extent of cross-linking, determined from the proportion of radioactive lysine in epsilon-(gamma-glutamyl) lysine after exhaustive proteolysis, was similar to that in stratum corneum. The properties of the cornified envelopes (insolubility in detergent and reducing agents, and solubility following proteolytic digestion) are readily explained by a structure consisting of a cross-linked protein lattice.
Related Concept Videos
Renewal of Skin Epidermal Stem Cells
Clinical Applications of Epidermal Stem Cells
Classification of Epithelial Tissues: Stratified Epithelium
Cells of the Epidermis
The cells in all these layers except the stratum basale are called keratinocytes, a type of cell that manufactures and stores the protein keratin. The keratinocytes in the stratum corneum are dead and regularly slough away, being replaced by cells from...
Papillary Dermis
The dermis might be considered the "core" of the integumentary system, as distinct from the epidermis and hypodermis. It contains blood and lymph vessels, nerves, and other structures, such as hair follicles and sweat glands. The dermis is made of two layers of connective tissue that comprise an interconnected mesh of elastin and collagenous fibers, produced by fibroblasts.
Papillary Layer
The papillary layer is made of loose, areolar connective tissue, which means the collagen...
Layers of the Epidermis
Stratum Basale
Stratum basale, also known as the stratum germinativum, is the deepest layer of the epidermis. It is composed of a single layer of actively dividing cells called basal cells or basal keratinocytes. These cells constantly undergo cell division to replenish the upper layers of the epidermis. Additionally, melanocytes, which...

