Immunologic cross-reaction of stratum corneum basic protein and a keratohyalin granule protein.
Antiserum to the stratum corneum basic protein (SCBP) of newborn rat epidermis was used to test for cross-reactive proteins in extracts of skin and in tissue sections. The antibody reacts strongly with epidermal extracts but very poor with dermal extracts. Buffer extracts of epidermis give a reaction of partial identity or identity with the antigen, SCBP. Urea extracts of isolated stratum corneum give a reaction of identity with SCBP. When the proteins of these extracts are separated by SDS polyacrylamide gel electrophoresis, the immunoreactive peak in the 4 M urea extract corresponds to the 49,000 MW SCBP. The immunoreactive peak in the 1 M potassium phosphate extract corresponds to a 52,000 MW protein. This protein is rapidly and transiently labeled after injection of 3H-histidine into newborn rats, in contrast to the SCBP which is labeled after a 5-hr lag. The 52,000 MW protein appears to be an immunologically related precursor of the SCBP. Immunoreactive proteins were localized in tissue sections by the indirect immunoperoxidase method. A strong positive reaction was seen in keratohyalin granules and in the stratum corneum. The reaction of keratohyalin granules corroborates the extraction of a cross-reactive protein by 1 M potassium phosphate, a method for extraction of keratohyalin granules from epidermis. These results are consistent with the hypothesis that a protein of 52,000 MW is present in keratohyalin and is converted to the SCBP (49,000 MW) concomitantly with the conconversion of a granular cell to a stratum corneum cell.
D000818:Animals; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D006818:Hyalin / Q000276:immunology*; D005779:Immunodiffusion; D007124:Immunoenzyme Techniques; D011506:Proteins / Q000276:immunology*; D051381:Rats; D012867:Skin / Q000276:immunology*
D011506:Proteins