Modified trafficking patterns for arrestin and G-protein-coupled receptors via arrestin-ubiquitin chimera
The present invention relates to a modified arrestin which includes an arrestin molecule and a ubiquitin molecule. This modified arrestin has an increased affinity for a GPCR, and traffics with the GPCR into endosomes. The present invention further relates to a method of screening compounds and sample solutions for a GPCR agonist, antagonist, inverse agonist, or desensitization active compound. The modified arrestin is useful in the methods of the present invention.
1. An arrestin chimera comprising a naturally occurring beta-arrestin-2 and a naturally occurring ubiquitin moiety, wherein the arrestin chimera has an increased affinity for a GPCR, as compared to the affinity of a wild-type arrestin for a GPCR, and wherein increased affinity means that the arrestin chimera remains associated with the GPCR and traffics with the GPCR into endosomes, and wherein the arrestin chimera does not dissociate from the GPCR at or near the plasma membrane.
2. The arrestin chimera of claim 1 , wherein the naturally occurring ubiquitin moiety or fragment of ubiquitin is fused in frame to the naturally occurring beta-arrestin-2.
3. The arrestin chimera of claim 1 , wherein the naturally occurring ubiquitin moiety is not susceptible to deubiquitination.
4. The arrestin chimera of claim 1 , wherein the naturally occurring ubiquitin moiety is linked to the 5′ or 3′ end of the arrestin.
5. The arrestin chimera of claim 1 , wherein the chimera further comprises a label, and wherein the label is a radioisotope, an epitope tag, an affinity label, an enzyme, a fluorescent group, or a chemiluminescent group.
6. The arrestin chimera of claim 1 , wherein the arrestin chimera comprises the amino acid sequence of SEQ ID NO:2.
7. The arrestin chimera of claim 1 , wherein the ubiquitin moiety comprises one or more ubiquitin chains.
8. The arrestin chimera of claim 1 , wherein the GPCR is a class A GPCR.
9. The arrestin chimera of claim 1 , wherein the arrestin chimera increases the internalization of the GPCR.