Species-dependent immunological differences between vertebrate brain tubulins.

The antigenic similarities and differences between highly purified brain tubulins from lamb, mouse, and chick embryo have been examined using rabbit antisera prepared against each of these tubulins. These antisera are capable of binding 125I-labeled tubulin in homologous or heterologous combinations, demonstrating immunological similarity between the tubulins. However, there are quantitative differences in the maximum amount of binding observed. Differences between the tubulins were further resolved by radioimmunoassays, comparing the ability of each of the tubulins to inhibit the binding of each 125I-labeled tubulin to each antiserum. Competition curves generated for all possible combinations revealed quantitative immunological differences between the tubulins that imply different densities of shared antigenic determinants on all three tubulins and a unique determinant on the chick tubulin molecule.