Covalent change in the major intrinsic polypeptide (MIP26K) during cataract development in the streptozotocin-induced diabetic rat.

Antisera to synthetic peptides corresponding to residues 229-237, 252-259, and 256-263 have been used to quantitatively bind to the 19.5K, 24.0K, and 26.5K forms of the Major Intrinsic Polypeptide (MIP26K) of lens membrane from the streptozotocin-induced diabetic rat. The binding ratio of anti-229/anti-252 for the 19.5K component, and the binding ratio of anti-252/anti-256 for the 26.5K component, both increase only during the opacification process of the diabetic lens. Together, these results demonstrate that various forms of the MIP26K molecule undergo covalent modification during cataractogenesis of the diabetic rat lens, and that the degree of this change as monitored by binding of the anti-MIP26K peptide sera correlates with severity of the lens opacification.