An N-acetylgalactosaminyltransferase and its acceptor in embryonic chick neural retina exist in interconvertible particulate forms depending on their cellular location.

Abstract

The N-acetylgalactosaminyltransferase activity and its associated endogenous acceptor present in neural retina cells from embryonic chicks can be separated into three distinct forms which migrate to different densities upon centrifugation in sucrose gradients. Two of these forms, termed L and H, are also present in preparations of plasma membranes. Dissociation of tissues into single cells by trypsin results in populations lacking the cell-surface forms of transferase activity towards endogenous acceptor. This loss can be prevented by including 1 mM Ca2+ in the trypsin-dissociation medium. Reacquisition of cell-surface activity among trypsin dispersed cells occurs with time in culture. In the presence of cycloheximide, the less dense particulate form, L. Appears first, with a concomitant decrease in the cytosol form. Upon removal of the block to protein synthesis, L is transformed into the denser from, H. Our studies suggest that peak H of transferase/acceptor polypeptide. The possible involvement of the transferase/acceptor in adhesion among neural retina cells is discussed.