This research proposal is designed to study the biochemistry of alpha-D-galactopyranosyl units in animal glycoproteins. We shall investigate the mode of biosynthesis, biodegradation and possible biological significance of this relatively rare carbohydrate group. Our model system will be the Ehrlich ascites tumor cell, the membrane of which contains a family of glycoproteins with alpha-D-galactosyl end groups. Alpha galactosyltransferase activity has been localized in the microsomal fraction of an Ehrlich cell homogenate. The alpha-glactosyltransferase(s) will be purified and studied with regard to its (their) physical-chemical and kinetic properties. Acceptor activity of the transferase(s) will be studied using a recently developed solid phase assay system. We will also assay for the activity of sialyl transferase(s) using solid phase oligosaccharide acceptors to determine whether a deficiency in this enzymatic activity leads to alpha-galactosylation.