Tissue and species specificity of BCP 54, the major soluble protein of bovine cornea

Abstract

The isolation and biochemical characterization of the most abundant intrinsic soluble protein of bovine cornea, BCP 54 (Bovine Corneal Protein, mol. wt 54000 daltons), have recently been described. We now report results of immunochemical experiments on the distribution of BCP 54 in bovine tissues. Antisera directed against BCP 54 were raised in rabbits and used in immunodiffusion analyses of soluble extracts of bovine tissues. BCP 54 was a significant constituent of all three corneal layers-epithelium, stroma and endothelium. This protein was also present in lens epithelium but it was absent from other bovine ocular tissues. Furthermore, BCP 54 was absent from all bovine non-ocular tissues tested. Proteins immunologically related to BCP 54 were present in human cornea and the corneas of the other mammalian species tested, swine and guinea pig. However, proteins analogous to BCP 54 were not detected in the three non-mammalian corneas tested: chicken, toad and fish. The absence of BCP 54 from bovine non-ocular tissues, in addition to the finding that similar proteins exist in the corneas of other mammalian species, suggests an important, although unknown, function for BCP 54 in the cornea.