Monoclonal antibodies reveal evolutionary conservation of alternative splicing of the alpha A-crystallin primary transcript

Because of their specificity and sensitivity, monoclonal antibodies are powerful tools in studies of protein structure and function. Therefore, we raised monoclonal antibodies against alpha A-crystallin and identified the antigenic determinant for two of these antibodies. Applying limited-digestion methods, we show that the region spanning residues 158-168 of alpha A-crystallin contains the epitope for the two monoclonal antibodies. These monoclonals were then used to study the occurrence in the lenses of different vertebrates of the elongated alpha Ains-crystallin chain, a product of alternative splicing. It appears that the mutational event resulting in the alternative splicing pattern of the alpha A-crystallin gene took place at least 70 million years ago. This alternative splicing phenomenon has been maintained in rodents and some other, unrelated mammals, but disappeared again in most mammalian lineages.