TY - JOUR
T1 - A2A and A2B adenosine receptors
T2 - The extracellular loop 2 determines high (A2A) or low affinity (A2B) for adenosine
AU - De Filippo, Elisabetta
AU - Hinz, Sonja
AU - Pellizzari, Veronica
AU - Deganutti, Giuseppe
AU - El-Tayeb, Ali
AU - Navarro, Gemma
AU - Franco, Rafael
AU - Moro, Stefano
AU - Schiedel, Anke C.
AU - Müller, Christa E.
PY - 2020/2
Y1 - 2020/2
N2 - A2A and A2B adenosine receptors (ARs) are closely related G protein-coupled receptor subtypes, which represent important (potential) drug targets. Despite their almost identical binding sites for adenosine, A2AARs are activated by low (nanomolar) adenosine concentrations, while A2BARs require micromolar concentrations. In the present study, we exchanged the extracellular loop 2 (ECL2) of the human A2AAR for that of the A2BAR. The resulting chimeric A2A(ECL2-A2B)AR was investigated in radioligand binding and cAMP accumulation assays in comparison to the wildtype A2AAR. While the ribose-modified adenosine analog N-ethylcarboxamidoadenosine (NECA) and its 2-substituted derivative CGS-21680 did not exhibit significant changes, adenosine showed dramatically reduced potency and affinity for the A2A(ECL2-A2B)AR mutant displaying similarly low potency as for the wt A2BAR. Supervised molecular dynamics simulation studies predicted a meta-binding site with high affinity for adenosine, but not for NECA, which may contribute to the observed effects.
AB - A2A and A2B adenosine receptors (ARs) are closely related G protein-coupled receptor subtypes, which represent important (potential) drug targets. Despite their almost identical binding sites for adenosine, A2AARs are activated by low (nanomolar) adenosine concentrations, while A2BARs require micromolar concentrations. In the present study, we exchanged the extracellular loop 2 (ECL2) of the human A2AAR for that of the A2BAR. The resulting chimeric A2A(ECL2-A2B)AR was investigated in radioligand binding and cAMP accumulation assays in comparison to the wildtype A2AAR. While the ribose-modified adenosine analog N-ethylcarboxamidoadenosine (NECA) and its 2-substituted derivative CGS-21680 did not exhibit significant changes, adenosine showed dramatically reduced potency and affinity for the A2A(ECL2-A2B)AR mutant displaying similarly low potency as for the wt A2BAR. Supervised molecular dynamics simulation studies predicted a meta-binding site with high affinity for adenosine, but not for NECA, which may contribute to the observed effects.
KW - Adenosine
KW - Chimeric receptor
KW - Extracellular loop
KW - GPCR
KW - Radioligand binding
KW - cAMP
UR - http://www.scopus.com/inward/record.url?scp=85078389342&partnerID=8YFLogxK
U2 - 10.1016/j.bcp.2019.113718
DO - 10.1016/j.bcp.2019.113718
M3 - Article
SN - 0006-2952
VL - 172
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
M1 - 113718
ER -