Immunochemical comparison of histidine-rich protein in keratohyalin granules and cornified cells

(1) Combination of techniques for extraction and purification of histidine rich protein established by several investigators were employed for comparison of histidine-rich protein in granular cells and cornified cells of newborn rats. (2) Histidine-rich protein extracted from the same cell fraction by two different techniques either in 1 M potassium phosphate buffer (Ugel) or in 4 M urea (Dale) showed identical elution profiles on CM 52 cellulose ion exchange chromatography and the same SDS polyacrylamide gel electrophoretic patterns. (3) Histidine-rich protein from granular cells contained polypeptides of larger molecular sizes than those in histidine-rich protein from cornfield cells, although amino acid composition of the two histidine-rich protein was non-distinguishable (histidine residue was more than 7%). (4) Antibodies raised in rabbits by injection of histidine rich protein from granular cells and that from cornfield cells immunologically cross-reacted. Furthermore, the antisera were found to be reactive over both keratohyalin granules and cornified cells, but not epidermal cells of the lower strata.