The glycosaminoglycan components of proteoglycans are biosynthesized and modified in the golgi apparatus by highly organized carbohydrate transfer enzymes and sulfotransferases. The purpose of this project is to investigate the functional organization and subcellular localization of these enzyme complexes. Brefeldin A is a chemical which specifically blocks anterograde protein transport within the golgi apparatus. It was used to disrupt the normal biosynthetic processes for adding glycosaminoglycan chains onto proteoglycans. When ovarian granulosa cells were treated with Brefeldin A, dermatan sulfate proteoglycan synthesis was abolished whereas heparan sulfate proteoglycan synthesis was only partially inhibited, suggesting that dermatan sulfate and heparan sulfate assembly on proteoglycans occurs in different subcellular compartments. The finding that only normal heparan sulfate protein core proteins were substituted with heparan sulfate chains in the presence of the drug indicated that glycosylation enzymes are highly specific to core proteins. Topics of present interest include elucidation of core protein structure which determines highly specific glycosylation enzymes.
