Regional differences in protein synthesis within the lens of the rat.

Utilization of S-methionine by cells of the rat lens was studied by combined autoradiographic and chemical techniques. Part of the methionine teas converted to cysteine, glutathione, and taurine. Protein synthesis was essentially restricted to the lens cortex, and appeared to be largely attributable to growth. One day after injection, over 90 per cent of total lens radioactivity was recovered from the cortex, most of it in water-soluble protein. Eight labeled protein fractions were separated. Continued peripheral addition of new fibers progressively buried the labeled cells within the body of the lens, so that at 4 weeks the proportion of total radioactivity recovered from the deeper fibers was increased. Insoluble protein (albuminoid) appeared to be largely derived from the precipitation of certain soluble proteins in the lens nucleus. Such selective insolubilization may account for the differing patterns of soluble protein observed in the inner and outer parts of the lens.