Characterisation of eight monoclonal antibodies to involucrin.

Involucrin is a precursor of the insoluble protein envelope that is assembled in the outermost layers of the epidermis. The coding sequence of the protein contains a number of short tandem repeats that have been greatly altered during mammalian evolution. We have characterised eight mouse monoclonal antibodies raised against human involucrin, all of which bind to the protein in immunoprecipitation, immunoblot and immunohistochemical preparations. Each antibody was screened for cross-reactivity with gorilla, owl monkey, dog and pig involucrin and with a fragment of the human protein, expressed in lambda gt 11, that includes the entire early region of the modern segment of repeats. Three antibodies recognised involucrin in all of these assays. Four antibodies recognised primate involucrins and the lambda gt 11 fragment. One antibody, which showed cross-reactivity with lower molecular weight proteins, only recognised primate involucrins and therefore bound outside the early region of the modern segment. Since the antibodies can be used to detect involucrin both biochemically and histologically, in a range of species, they will have applications in further studies of the expression, function and evolution of the protein.