N-cadherin is stably associated with and is an acceptor for a cell surface N-acetylgalactosaminylphosphotransferase.

Calcium-dependent cell-cell adhesion among embryonic chick neural retina cells is mediated by N-cadherin, a 130,000-Da integral membrane protein. We have reported that the ability of chick neural retina cells to form calcium-dependent cell-cell adhesion is also correlated with the presence of an N-acetylgalactosaminyltransferase at the cell surface (Balsamo, J., and Lilien, J. (1982) J. Biol. Chem. 257, 349-354). This enzyme transfers N-acetylgalactosaminephosphate to endogenous acceptors (Balsamo, J., Pratt, R. S., and Lilien, J. (1986) Biochemistry 25, 5402-5407) and is tightly associated with these acceptors forming a complex which can be isolated from neutral detergent extracts of plasma membranes. We now report that N-cadherin is present in the complex and is an acceptor for the N-acetylgalactosaminylphosphotransferase. Antibodies prepared against N-cadherin precipitate the transferase containing complexes from neutral detergent extracts; however, when the complexes are dissociated by treatment with sodium dodecyl sulfate prior to immunoprecipitation, only N-cadherin is precipitated. Similarly, anti-transferase antibodies immunoprecipitate N-cadherin containing complexes prior to disruption of the complex with sodium dodecyl sulfate. Catalysis of the transferase reaction in the complex results in the transfer of N-acetylgalactosamine phosphate to oligosaccharide chains on N-cadherin. Glycosylation of N-cadherin by the transferase also occurs in situ; labeling of retina cells with [32P] orthophosphate results in N-cadherin molecules containing terminal N-acetylgalactosamine linked to an oligosaccharide chain via a phosphodiester bond.