G protein-coupled receptor (GPCR) for adenosine that plays significant roles in various physiological processes including immune regulation, cardioprotection and neuroprotection (PubMed:38627384, PubMed:40825947, PubMed:9837869). Also acts as a receptor for adenosines containing N(6)-methylated adenine (m6A) post- transcriptional modification, which are derived from the degradation of RNAs (mRNAs, rRNAs and tRNAs): activated by N(6)-methyladenosine (m6A), N(6),N(6)-dimethyladenosine (m6,6A) and N(6)-isopentenyladenosine (i6A) (PubMed:33472058, PubMed:39511145). Preferentially couples to the inhibitory G protein (Gi), leading to the suppression of adenylate cyclase activity and a reduction in intracellular cyclic AMP levels (PubMed:33472058, PubMed:38627384). Upon adenosine binding, mediates cardioprotection in cardiomyocytes through anti-apoptotic effects primarily via the ERK1/2 pathway as well as the PI3K pathway (PubMed:9837869). In the central nervous system, participates in the modulation of synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD) in the hippocampus (By similarity). In lung mast cells, receptor activation contributes to the type I allergic response by facilitating mast cell degranulation and histamine release (By similarity). Highly expressed in inflammatory cells such as neutrophils and mast cells, inhibits neutrophil degranulation and reduces superoxide production, thereby modulating inflammatory responses (PubMed:9164961). {ECO:0000250|UniProtKB:P28647, ECO:0000250|UniProtKB:Q61618, ECO:0000269|PubMed:33472058, ECO:0000269|PubMed:38627384, ECO:0000269|PubMed:39511145, ECO:0000269|PubMed:40825947, ECO:0000269|PubMed:9164961, ECO:0000269|PubMed:9837869}. [Isoform 2]: Receptor for adenosine. The activity of this receptor is mediated by G proteins which inhibits adenylyl cyclase (PubMed:8234299). . This is the function of Ensembl gene identifier ENSG00000282608 (ADORA3, adenosine A3 receptor).