[Distribution of calmodulin in bovine lens; changes as a function of age]

Calmodulin contents were determined by radioimmunoassay in Bovine lens layers as a function of age. The values in the epithelial cell layer appeared to be strikingly higher than in the cortical layer where they were still higher than in the nucleus. In the lens epithelial cell layer the calmodulin levels were maintained when calf was compared with adult or aged animals (100-110 ng/mg protein). Nevertheless, a decrease of calmodulin content was observed in the lens epithelium of very old animals (65 ng/mg prot.). In the cortical layer, the calmodulin content was very low and variable during aging (11-18 ng/mg prot.). In the lens nucleus the extremely low amount of calmodulin still decreased during aging (10-0.2 ng/mg prot.). The significance of these data was discussed.