
pmid: 18938240
Clathrin-mediated endocytosis is a complex process regulated at many different levels. We showed previously that activation of the angiotensin type 1 receptor (AT1R), which belongs to the G protein-coupled receptor (GPCR) family, leads to c-Src-dependent tyrosine phosphorylation of beta2-adaptin, a subunit of the clathrin adaptor AP-2. The phosphorylation of beta2-adaptin on tyrosine residue 737 (Y737) negatively regulates its interaction with betaarrestin, another important clathrin adaptor for GPCR internalization. Here we sought to determine whether AP-2 phosphorylation represents a general mechanism for different receptors internalizing through the clathrin pathway. Using a specifically designed antibody against the phosphorylated form of Y737 on beta2-adaptin, we demonstrate that this residue is phosphorylated by AT1R in different cell types like HEK293, COS-7 and vascular smooth muscle cells. Using RNA interference approaches, we reveal that this agonist-mediated event is both betaarrestin- and c-Src-dependent, and that it occurs at the plasma membrane in clathrin-coated vesicles (CCVs). We further show that this is not only a common event employed by other GPCRs like the beta2-adrenergic, vasopressin V2, bradykinin type 2, platelet-activating factor and endothelin A receptors but that the epidermal growth factor receptor is capable of eliciting the phosphorylation of AP-2 in CCVs. Our results imply that tyrosine phosphorylation of Y737 on beta2-adaptin is a common regulatory mechanism employed by different receptors undergoing clathrin-dependent endocytosis, and suggest a wider function for this event than originally anticipated.
Arrestins, Angiotensin II, Adaptor Protein Complex 2, Clathrin-Coated Vesicles, Protein-Tyrosine Kinases, Clathrin, Endocytosis, Receptor, Angiotensin, Type 1, Cell Line, CSK Tyrosine-Protein Kinase, ErbB Receptors, Fluorescent Antibody Technique, Direct, Gene Knockdown Techniques, COS Cells, Chlorocebus aethiops, Animals, Humans, Adaptor Protein Complex beta Subunits, Amino Acid Sequence, Phosphorylation
Arrestins, Angiotensin II, Adaptor Protein Complex 2, Clathrin-Coated Vesicles, Protein-Tyrosine Kinases, Clathrin, Endocytosis, Receptor, Angiotensin, Type 1, Cell Line, CSK Tyrosine-Protein Kinase, ErbB Receptors, Fluorescent Antibody Technique, Direct, Gene Knockdown Techniques, COS Cells, Chlorocebus aethiops, Animals, Humans, Adaptor Protein Complex beta Subunits, Amino Acid Sequence, Phosphorylation
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