Using isozyme-specific anti-peptide antisera against peptides from theα-,β-,γ-,δ-,σ-, andϵ-isoforms of brain protein kinase C (PKC), we have identified proteins in bovine lens epithelial cells, in culture, that were reactive with these antisera. Western blots of lens epithelial cell homogenates showed that PKC-αántisera reacted with a major protein, and PKC-γantisera reacted with a minor protein. When the lens epithelial cells were cultured in media supplemented with 40 mM galactose, to model the conditions of sugar cataracts, a decrease in PKC-γ, but not in PKC-αwas observed. These were normalized if the cells were cultured in 40 mM galactose media supplemented with an inhibitor of aldose reductase, Tolrestat (10μM). These results suggest that changes in PKC isoforms occur in the galactosemic diabetic state.