beta2-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 of the clathrin-coated vesicle constituents. How these cycles are regulated is still not fully known but previous studies have indicated that phosphorylation of coat subunits may play a role. Here we describe that beta2-adaptin undergoes cycles of phosphorylation/de-phosphorylation in intact cells. Thus, beta2-adaptin was constitutively de-phosphorylated by serine/threonine protein phosphatase 2A and phosphorylated by a staurosporine-sensitive kinase in vivo. Confocal laser scanning microscopy demonstrated that phosphorylated AP2 complexes were found more evenly distributed at the plasma membrane compared to non-phosphorylated AP2 complexes which were found in aggregates. Finally, we found that phosphorylation of beta2-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 vesicles.
Lauritsen
J P
JP
Institute of Medical Microbiology and Immunology, University of Copenhagen, Blegdamsvej 3, DK-2200, Copenhagen, Denmark.
Menné
C
C
Kastrup
J
J
Dietrich
J
J
Odum
N
N
Geisler
C
C
D033966:Adaptor Protein Complex beta Subunits; D000935:Antifungal Agents / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D004705:Endocytosis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D019169:Jurkat Cells; D008387:Marine Toxins; D008565:Membrane Proteins / Q000737:chemistry*; D018613:Microscopy, Confocal; D019319:Okadaic Acid / Q000494:pharmacology; D010080:Oxazoles / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D010766:Phosphorylation; D011494:Protein Kinases / Q000737:chemistry*; D054648:Protein Phosphatase 2; D011714:Pyrans; D013141:Spiro Compounds; D019311:Staurosporine / Q000494:pharmacology
D033966:Adaptor Protein Complex beta Subunits; D000935:Antifungal Agents; D004791:Enzyme Inhibitors; D008387:Marine Toxins; D008565:Membrane Proteins; D010080:Oxazoles; D011714:Pyrans; D013141:Spiro Compounds; C053079:tautomycin; D019319:Okadaic Acid; C059041:calyculin A; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D019311:Staurosporine