The capacity of the retina to carry out the biosynthesis of the lipid-activated carbohydrates and their use as substrates in the biosynthesis of endogenous glycoproteins in this tissue has been demonstrated in previous studies by this laboratory. The participation of these compounds in the biosynthesis of the carbohydrate chains of the specific glycoprotein, rhodopsin, will be investigated. Mannose and glucosamine will be removed from rhodopsin by glycosidase action on the purified visual pigment or from rhodopsin still present in the rod outer segment. After purification, deglycosylated vitamin A-containing derivatives resulting from this procedure, as well as other analogues of visual pigment, will be used as potential acceptor molecules in glycosyltransferase reactions. Dolichyl phosphate-mannose, lipid-linked oligosaccharides, as well as derivatives of retinyl phosphate will be examined as substrates in these reactions. The cleavage of the sugar groups from rhodopsin and from rhodopsin-peptides by purified glycosidases and by preparations from the pigment epithelium from cattle, and from the normal and RCS rat will be investigated.