THE EFFECTS OF PHOSPHORYLATION ON THE FUNCTIONAL REGULATION OF AN EXPRESSED RECOMBINANT HUMAN DOPAMINE TRANSPORTER

Metabolic labeling experiments were performed using eukaryotic cells t ransfected with the human dopamine (DA) transporter cDNA. Autophosphor ylation in the presence and absence of the transporter substrate DA, w as analyzed. Dopamine transporter (DAT) was phosphorylated in the abse nce of DA and dephosphorylated in the presence of the substrate. The f unctional significance of this phenomenon was checked by incubating ce lls with phosphorylation promoting agents, all of which reduced substr ate uptake and ligand binding significantly. It is shown that at least one site of phosphorylation on DAT is a serine residue. These experim ents suggest that the state of phosphorylation of the DAT may play an important role in its biological function.