N-linked glycosylation of platelet P2Y12 ADP receptor is essential for signal transduction but not for ligand binding or cell surface expression

P2Y12 receptor is a Gi-coupled adenosine diphosphate (ADP) receptor with a critical role in platelet aggregation. It contains two potential N-linked glycosylation sites at its extra cellular amino-terminus, which may modulate its activity. Studies of both tunicamycin treatment and site-directed mutagenesis have revealed a dispensable role of the N-linked glycosylation in the receptor's surface expression and ligand binding activity. However, the non-glycosylated P2Y12 receptor is defective in the P2Y12-mediated inhibition of the adenylyl cyclase activity. Thus the study uncovers an unexpected vital role of N-linked glycans in receptor's signal transducing step but not in surface expression or ligand binding. (C) 2004 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.