Protein–protein interactions and lens transparency

Past studies have identified posttranslational modifications of human lens proteins occurring during cataract formation, and have also demonstrated that protein–protein interactions exist between different lens crystallins. Based upon current theories of lens transparency, these posttranslational modifications and their possible effects upon crystallin interactions may be the key to understanding why the lens is able to transmit light, and why transmission is decreased during cataractogenesis. This review will summarize current knowledge of posttranslational modifications during human cataractogenesis, and will propose their possible role in protein–protein interactions that are thought to be necessary for lens transparency. Based upon this premise, model systems will be described that will test the validity of the theory.