title: Binding of AP-2 adaptor complex to brain membrane is regulated by phosphorylation of proteins.
abstract: Phosphorylation of proteins appears as a key process in early steps of clathrin coated vesicle formation. Here, we report that treatment of post-nuclear fraction with alkaline phosphatase induced redistribution of alpha subunits of AP-2 adaptor complex to cytosol and this effect was higher in the alpha2 subunit. A high serine phosphorylation status of alpha subunits correlated with the higher affinity of AP-2 to membranes. Using a simple binding assay, where membranes were incubated with either purified adaptors or cytosols, we observed an inhibitory effect of tyrphostin, a tyrosine kinase inhibitor, on the binding of AP-2 to membranes, but also an unexpected decrease induced by the phosphatase inhibitor cyclosporine. We also show an inhibitory effect of ATP mediated by cytosolic proteins, although it could not be related to the phosphorylation of AP-2, suggesting an action upstream a cascade of phosphorylations that participate in the regulation of the assembly of AP-2 to membranes.
authors.affiliation: Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza (5500), Argentina. aalberdi@fcm.uncu.edu.ar
authors.forename: A
authors.initials: A
authors.lastname: Alberdi
authors.forename: T
authors.initials: T
authors.lastname: Sartor
authors.forename: M A
authors.initials: MA
authors.lastname: Sosa
mesh_terms: D033962:Adaptor Protein Complex 2 / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010770:Phosphotransferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021122:Protein Subunits / Q000378:metabolism; D051381:Rats
chemical_list: D033962:Adaptor Protein Complex 2; D047428:Protein Kinase Inhibitors; D021122:Protein Subunits; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D000469:Alkaline Phosphatase