beta 2-Adaptin is constitutively de-phosphorylated by serine/threonine protein phosphatase PP2A and phosphorylated by a staurosporine-sensitive kinase

Clathrin-mediated endocytosis includes cycles of assembly and disassembly o f the clathrin-coated vesicle constituents. How these cycles are regulated is still not fully known but previous studies have indicated that phosphory lation of coat subunits may play a role. Here we describe that beta 2-adapt in undergo es cycles of phosphorylation/de-phosphorylation in intact cells. Thus, beta 2-adaptin was constitutively de-phosphorylated by serine/threon ine protein phosphatase 2A and phosphorylated by a staurosporine-sensitive kinase in vivo. Confocal laser scanning microscopy demonstrated that phosph orylated AP2 complexes were found more evenly distributed at the plasma mem brane compared to non-phosphorylated AP2 complexes which were found in aggr egates. Finally, we found that phosphorylation of beta 2-adaptin correlated with inhibition of clathrin-mediated endocytosis. Our results support the hypothesis that phosphorylation/de-phosphorylation of coat proteins plays a regulatory role in the assembly/disassembly cycle of clathrin-coated vesic les. (C) 2000 Elsevier Science B.V. All rights reserved.