Membrane alterations during cataract development in the Nakano mouse lens.

The anterior cortical fiber cells of the 12-day-old Nakano mouse lens revealed an extremely large number of gap junctions, the appearance of which was identical to those of the normal lens. Although the number of gap junctions of the cells in the same area at 29 days was comparable to that seen at 12 days, the size of each junction became smaller with cataract formation. The junctions were almost absent in the anterior cortical cells in 7-month-old Nakano mice. Biochemical analysis revealed that the 26,000 MW polypeptide closely associated with the cell membrane was lower in amount in the membrane preparation of the 29-day Nakano mouse lens than in the 12-day lenses. With the membrane fractions of lenses from 90-day Nakano mice, the absence of a major 26,000 NW polypeptide component correlates with the decrease in gap junction structures. The alternations in the gap junctions and membrane associated polypeptides of the Nakano lens may be linked with the steps leading to cataract development.