Heterogeneity of bovine snout epidermal prekeratin

The prekeratin of the snout of cows was extracted with 0-1 mol/l citric acid-sodium citrate buffer, pH 2-6. The results of equilibrium ultracentrifugation analyses of this prekeratin strongly suggest that this protein is not homogeneous. This conclusion is in accordance with the observations of two other investigators whose data infer that there is no major homogeneous keratin precursor in cow's lip or snout epidermis.