Reengineering the Collision Coupling and Diffusion Mode of the A2A-adenosine Receptor

Abstract

Background: The A2A receptor engages Gs by restricted collision coupling and lacks a palmitoyl moiety in its C terminus.Results: Engineering palmitoylated cysteine into the C terminus relieved restricted collision coupling and resulted in accelerated diffusion of the agonist-liganded A2A receptor.Conclusion: Restricted collision coupling arises from limits imposed on receptor diffusion.Significance: Agonist induced confinement of the A2A receptor in a structure consistent with a lipid raft.

Recruitment of a Cytoplasmic Chaperone Relay by the A2A Adenosine Receptor

“…Hence, the candidate binding site is likely to reside in the C terminus. This is also predicted by the COPII-chaperone exchange model (5). Consistent with this conjecture, a fusion protein comprising the A 2A receptor C terminus and MBP (A 2A R C-tail) bound purified HSP90α (Fig.…”

“…Truncation of the C-terminal tail of both the A 2A and the A 1 receptor results in a decrease or even in a loss of their cell surface expression (14, 44). However, we failed to detect any interaction between DRiP78 and the A 2A receptor (not shown), possibly because the A 2A receptor lacks the palmitoylated cysteine at the end of helix 8 (5). …”

“…37). The recently proposed chaperone-COPII exchange posits a crucial role of the C terminus as a binding site for the cytosolic folding machinery (5). The current experiments were designed to identify the nature of these cytosolic factors.…”

“…The A 2A receptor does not carry a cysteine residue at the end of the C-terminal helix 8, which, in the vast majority of rhodopsin-like GPCRs, is the site of palmitoylation (4). This suggests that the C terminus of the A 2A receptor is not constrained by a lipid anchor and is hence more flexible (5). These two features, relative length and flexibility, may combine to afford the interaction of the A 2A receptor with many additional accessory proteins other than G proteins, arrestins, and G protein receptor kinases.…”

Regulation of TrkB receptor translocation to lipid rafts by adenosine A2A receptors and its functional implications for BDNF-induced regulation of synaptic plasticity

“…No changes were observed in the cholesterol levels present in the raft fraction #2 (11.0±1.1 in control and 11.6±0.9 μg/ml after 05, n=3). These results do not exclude the importance of lipid rafts for optimal A 2A receptor signalling [30], but strongly suggest that ligand affinity and density of this receptor are conserved while interfering with lipid raft integrity.…”