Monoclonal antibodies reveal evolutionary conservation of alternative splicing of the αA‐crystallin primary transcript

Abstract

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 epitoipe 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.