Binding of AP-2 adaptor complex to brain membrane is regulated by phosphorylation of proteins

ANTONIO ALBERDI; TIRSO SARTOR; MIGUEL A. SOSA

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS

Elsevier

Año: 2005 vol. 330 p. 695 - 700

0006-291X

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 a subunits of AP-2 adaptor complex to cyto- sol and this e .ect was higher in the a subunit.A high serine phosphorylation status of a subunits correlated with the higher a .nity of AP-2 to membranes.Using a simple binding assay,where membranes were incubated with either puri .ed adaptors or cytosols,we observed an inhibitory e .ect 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 e .ect of ATP mediated by cytosolic pro- teins,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.a subunits of AP-2 adaptor complex to cyto- sol and this e .ect was higher in the a subunit.A high serine phosphorylation status of a subunits correlated with the higher a .nity of AP-2 to membranes.Using a simple binding assay,where membranes were incubated with either puri .ed adaptors or cytosols,we observed an inhibitory e .ect 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 e .ect of ATP mediated by cytosolic pro- teins,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.a subunits correlated with the higher a .nity of AP-2 to membranes.Using a simple binding assay,where membranes were incubated with either puri .ed adaptors or cytosols,we observed an inhibitory e .ect 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 e .ect of ATP mediated by cytosolic pro- teins,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. 2005 Elsevier Inc.All rights reserved.