Electrophoresis of soluble proteins extracted from cell suspensions of neonatal rat epidermis

The identification of fibrous proteins in fetal rat epidermis by electrophoretic and immunologic techniques

Two proteins have been identified in extracts of fetal rat skin which are related to the two major fibrous proteins of newborn rat stratum corneum. The relative amount of these proteins increases daily from the 16th to the 20th day (d) of gestation when judged by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and immunoelectrophoresis using antibody to the purified fibrous protein. Two-dimensional analysis by SDS-polyacrylamide gel electrophoresis and immunoelectrophoresis demonstrates that these two proteins are the only cross-reactive species in the fetal skin from 16d to 19d development. Some additional lower-molecular-weight components can be detected at 20d and 21d. In double-diffusion analysis, cross-reactive proteins in 19d fetal extracts show partial identity but have fewer antigenic sites than proteins in 20d extracts. The 20d protein shows a reaction of identity with purified newborn fibrous protein. Immunofluorescence studies on fetal skin support the prescence of cross-reacting components at 16d development related to the newborn fibrous protein. Intensity of fluorescence increases at 18d and 20d in the spinous and granular cell cytoplasm and in the keratohyaline granules. The stratum corneum, first seen at 20d, is intensely fluorescent. The cellular localization and time of appearance of the cross-reactive proteins suggest that they may be associated with tonofilaments.

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins of newbonr rat skin. II. Keratohyalin and stratum corneum proteins

Keratohyalin extracts from newborn rat epidermis were prepared by potassium phosphate and citric acid-detergent extraction procedures. These preparations were compared by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and amino acid analysis. The major band of the potassium phosphate extract has a molecular weight of 48,000. The major bands of the citric acid-detergent preparation have molecular weights of 64,000, 61,500, 57,000 and 54,000. Electrophoresis of S-carboxylmethylated (SCM)-fibrous protein results in two major bands of approximately 57,000 and 64,000. SDS gels of the two preparations of keratohyalin and the SCM-fibrous protein were compared with gels of the insoluble proteins of granular and eluted cornified cells. All of the major bands in the preparations of keratohyalin can be seen in gels of the granular preparation. The two SCM-fibrous protein bands correspond with two prominent bands in gels of the cornified cell preparation. Two bands of the citric acid-extracted keratohyalin sample also have the same mobility. The major band of the potassium phosphate-extracted preparation of keratohyalin corresponds with a third prominent band of the cornified cell preparation. These results suggest that biochemical components of the preparations of keratohyalin are present in both the granular and the cornified layers of newborn rat epidermis.

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins of newborn rat skin. I. Cell strata and nuclear proteins

The proteins obtained from separated cells of neonatal rat dermis, four cell populations of epidermis, and an epidermal nuclear preparation were analyzed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Comparison of the results of the insoluble proteins of the dermis and epidermis show no similarity of the major protein bands, indicating the effective separation of the dermis and epidermis and absence of cross-contamination. The gels of the soluble proteins of the basal, spinous, and granular layers of the epidermid are very similar. Only the pattern of bands of the cornified cells differs in that some of these bands are absent and at least three new bands are present. The insoluble proteins have specific differences in the protein content related to the cell structure. An example is the nuclear protein bands which correspond with the most prominent bands in the gels of basal and spinous layer proteins, but are absent, with the possible exception of one band, from gels of cornified cell proteins.