Plants restrict use of 'Tipp-Ex proteins'

Plants have special corrective molecules at their disposal that can make retrospective modifications to copies of genes. However, it would appear that these 'Tipp-Ex proteins' do not have permission to work in all areas of the cell, only being used in chloroplasts and mitochondria. A study has now explained why this is the case. It suggests that the correction mechanism would otherwise modify copies that have nothing wrong with them, with fatal consequences for the cell.