STIMULATION OF THE SYNTHESIS OF SPECIFIC GLYCOPROTEINS IN CORNEAL EPITHELIUM BY VITAMIN-A

The uptake of labeled glucosamine into a specific, purified glycopeptide of corneal epithelium was stimulated twofold by incubating whole corneas of vitamin A-deficient rats with retinol. This glycopeptide was found to be a moiety of a glycoprotein isolated from the incubation medium. The synthesis of this glycoprotein from incubated vitamin A-deficient corneas was stimulated to normal levels with as little as 2 × 10-7 m added retinol in 3 hr; stimulation was 60% of maximum at 2 × 10-9 m-retinol. No such stimulation of synthesis was observed when normal corneas were incubated with retinol. The glycoprotein stimulated by the added retinol was not a glycosaminoglycan and took up no labeled sulfate; its origin is not conjunctival. It is probably derived from corneal epithelium. © 1979.