Characterization of the keratin filament subunits unique to bovine snout epidermis

Steinert [Biochem. J. (1975) 149, 39-48] reported that the alpha-keratin polypeptides (the subunits of the intracellular keratin filaments) of bovine hoof and snout epidermis are the same. We now demonstrate that this is not so: in addition to the seven polypeptides previously identified in hoof epidermis, snout epidermis also contains at least three other polypeptides of higher molecular weight. These unique polypeptides were isolated, purified and characterized. They are chemically and structurally very similar to the other polypeptides of bovine epidermis and readily polymerize in vitro with them to form native-type epidermal keratin filaments.