Covalent changes in MIP26K during aging of the human lens membrane

Rabbit antisera have been made to the C-terminal octapeptide of bovine MIP26K (residues 256-263) and to an octapeptide near the C-terminus (residues 252-259). Use of these antisera in Western blot analysis of membrane from young vs old human lenses, and from cortex vs nucleus of old human lenses, suggest age-related covalent changes in the C-terminus of MIP26K. These age-related changes in anti-256-263 and anti-252-259 sera can be mimicked by treatment of lens membrane with carboxypeptidase Y, suggesting the loss of 1-8 amino acid residues from the C-terminus of the 26,000 dalton form of MIP26K during aging of the normal human lens.