Subunit structure of the mouse epidermal keratin filament.

The two proteins which are the subunits of mouse epidermal keratin filaments have been isolated from fully differentiated epidermis (stratum corneum), viable differentiating cells and cells grown in culture. The proteins have molecular weights of 68 000 and 60 000, consist of families of very similar species, have common N-terminal (N-acetylserine) and C-terminal (glycine) residues, contain 35--40% alpha-helix and are immunologically cross-reacting. In mixtures, the two proteins polymerize in vitro into native-type keratin filaments that are 70--80 angstrom in diameter, up to 30 micrograms long, possess a characteristic alpha-type X-ray diffraction pattern and contain the subunits in the precise molar ratio of 1 : 2 or 2 : 1.

Ten-nanometer filaments of hamster BHK-21 cells and epidermal keratin filaments have similar structures.

The 10-nm filaments of baby hamster kidney (BHK-21) cells, when examined either in the form of native filament caps or polymerized in vitro, are long tubes of protein 8--10 nm in diameter. They contain about 42% alpha-helix, which, on the basis of x-ray diffraction data, is arranged in a coiled-coil conformation characteristic of proteins of the alpha type. The known structural properties such as morphology, dimensions, subunit composition, and ultrastructure of this fibrous protein are very similar to those of the mammalian epidermal keratin filament, to which it may therefore be related.

Biochemical evidence for keratinization by mouse epidermal cells in culture.

More than 70 percent of the urea-extractable proteins from mouse stratum corneum or from differentiated cells of mouse epidermis grown in culture are two proteins of molecular weight 68,000 (keratin I) and 60,000 (kerae are two proteins of molecular weight 68,000 (keratin 1) and 60,000 (keratin 2), which are present in equimolar amounts on polyacrylamide gels. These proteins are the subunits of the keratin filaments, because when isolated from stratum corneum or cells grown in culture they form native-type epidermal keratin filaments in vitro. These observations provide biochemical evidence that epidermal cells grown in culture synthesize the major differentiation products of the epidermis.

The polypeptide composition of bovine epidermal alpha-keratin.

1. The polypedtide chains that comprise the subunits of the tonofilaments, or th alpha-keratin component, of bovine epidermis were fractionated by combination of chromatography on DEAE-cellulose and preparative polyacrylamide-gel electrophoresis. 2.

The extraction and characterization of bovine epidermal alpha-keratin.

1. The alpha-fibrous protein (alpha-keratin) component of bovine epidermis has been extracted and characterized. 2.

Characterization of the proteins of guinea-pig hair and hair-follicle tissue.

This work forms a part of a study of the mechanism and control of protein synthesis in the hair follicle and concerns the characterization of the proteins of hair-follicle tissue and for comparative reasons those of the hair itself. 1. Five different groups of reduced carboxymethylated proteins were delineated from both tissues; these were: group 1A proteins, which appeared to be aggregates of the group 2 proteins; group 1B proteins, soluble at pH4.