Arrestin function in G protein-coupled receptor endocytosis requires phosphoinositide binding

Abstract

Internalization of agonist-activated G protein-coupled receptors is mediated by non-visual arrestins, which also bind to clathrin and are therefore thought to act as adaptors in the endocytosis process. Phosphoinositides have been implicated in the regulation of intracellular receptor trafficking, and are known to bind to other coat components including AP-2, AP180 and COPI coatomer. Given these observations, we explored the possibility that phosphoinositides play a role in arrestin's function as an adaptor. High-affinity binding sites for phosphoinositides in β-arrestin (arrestin2) and arrestin3 (β-arrestin2) were identified, and dissimilar effects of phosphoinositide and inositol phosphate on arrestin interactions with clathrin and receptor were characterized. Alteration of three basic residues in arrestin3 abolished phosphoinositide binding with complete retention of clathrin and receptor binding. Unlike native protein, upon agonist activation, this mutant arrestin3 expressed in COS1 cells neither supported β 2 -adrenergic receptor internalization nor did it concentrate in coated pits, although it was recruited to the plasma membrane. These findings indicate that phosphoinositide binding plays a critical regulatory role in delivery of the receptor-arrestin complex to coated pits, perhaps by providing, with activated receptor, a multi-point attachment of arrestin to the plasma membrane.

Inositol hexakisphosphate kinase 2 sensitizes ovarian carcinoma cells to multiple cancer therapeutics

“…It is possible that InsP 5 PP, which contains a pyrophosphate linkage, may function as an energy source that facilitates DISC assembly or signal transduction to the caspase cascade. Proteins that bind IP 6 include the clathrin assembly proteins AP-2, AP-3, and AP-180 (involved in membrane fusion) (Norris et al, 1995;Voglmaier et al, 1992;Ye et al, 1995), the synaptotagmins (involved in exocytosis of synaptic vesicles) (Mehrotra et al, 2000) and arrestin (which acts as an adapter during endocytosis) (Gaidarov et al, 1999). All these proteins are closely associated with the plasma membrane.…”

Phosphatidylinositol 4,5-Bisphosphate Modifies Tubulin Participation in Phospholipase Cβ1Signaling

“…The binding of PIP 2 assists the targeting of these proteins to the membrane and facilitates their coupling with membrane-associated signaling molecules. Binding with high affinity to both the activated receptor and phosphoinositides was proposed to provide a multipoint attachment of ␤-arrestin and arrestin 3 to the plasma membrane (Gaidarov et al, 1999). Tubulin might enjoy a similar attachment.…”

Direct interaction of Cbl with pTyr 1045 of the EGF receptor (EGFR) is required to sort the EGFR to lysosomes for degradation

“…ß-arrestin is another sorting adaptor involved in clathrin-mediated endocytosis. ß-arrestin binds to PI(4,5)P 2 (Gaidarov et al, 1999a), clathrin and AP-2 (Goodman et al, 1996;Laporte et al, 1999) and is involved in endocytosis of G Protein-Coupled Receptors (GPCRs) (reviewed in Marchese et al, 2003a). Upon activation and phosphorylation of GPCRs and engagement of ß-arrestin, ß-arrestin is recruited to preexisting sites of clathrin assembly where it promotes rapid endocytosis of GPCRs (reviewed in Traub, 2003).…”