C-methyltransferase activity rRNA (adenine) methyltransferase activity rRNA (adenine(2503)-C2-)-methyltransferase activity https://github.com/geneontology/go-ontology/issues/26114 https://github.com/geneontology/go-ontology/issues/28183 https://github.com/geneontology/go-ontology/issues/9902 Catalysis of the reaction: adenosine2503 in 23S rRNA + 2 reduced [2Fe-2S]-[ferredoxin] + 2 S-adenosyl-L-methionine = 2-methyladenosine2503 in 23S rRNA + 5'-deoxyadenosine + L-methionine + 2 oxidized [2Fe-2S]-[ferredoxin] + S-adenosyl-L-homocysteine. MetaCyc:RXN-11586 RHEA:42916 molecular_function rRNA (adenine-C2-)-methyltransferase activity GO:0070040