Human Stratum Corneum Proteomics Reveals Cross-Linking of a Broad Spectrum of Proteins in Cornified Envelopes

The study investigated the composition and formation of the cornified protein envelope in the epidermis, focusing on the role of keratinocyte transglutaminase (TGM 1) defects in autosomal recessive congenital ichthyosis. Mass spectrometry analysis of purified envelopes revealed approximately 170 proteins, with keratins making up about 74% of the total. Non-keratin proteins like keratinocyte proline-rich protein, loricrin, and late envelope protein-7 were also significantly incorporated. The findings suggested that a variety of cellular proteins are integrated into the envelope, similar to observations in hair shafts and nail plates, and explained why the loss of specific envelope components had minimal effects on the epidermis. This protein profile provided a basis for future studies on envelope changes in pathological conditions.