Dioxygenase that demethylates RNA by oxidative demethylation: specifically demethylates N(6)-methyladenosine (m6A) RNA, the most prevalent internal modification of messenger RNA (mRNA) in higher eukaryotes (PubMed:29279410). Can also demethylate N(6)-methyladenosine in single-stranded DNA (in vitro) (By similarity). Requires molecular oxygen, alpha-ketoglutarate and iron (By similarity). Demethylation of m6A mRNA affects mRNA processing and export (By similarity). Required for the late meiotic and haploid phases of spermatogenesis by mediating m6A demethylation in spermatocytes and round spermatids: m6A demethylation of target transcripts is required for correct splicing and the production of longer 3'-UTR mRNAs in male germ cells (PubMed:23177736, PubMed:29279410). 2-oxoglutarate + an N(6)-methyladenosine in mRNA + O2 = an adenosine in mRNA + CO2 + formaldehyde + succinate Binds 1 Fe(2+) ion per subunit. Monomer. Widely expressed, with highest expression in testis (PubMed:23177736). In testis, present in almost all testicular cell types except elongating and elongated spermatids (at protein level) (PubMed:29279410). Among spermatogenic cells, present at high level in spermatocytes; medium levels in spermatogonia and lower levels in round spermatids (at protein level) (PubMed:29279410). Mice are viable, anatomically normal and reach adulthood but display impaired fertility resulting from apoptosis that affects meiotic metaphase-stage spermatocytes (PubMed:23177736, PubMed:29279410). Testes are significantly smaller and histological analysis of testis sections reveal aberrant tubular architecture and size (PubMed:23177736, PubMed:29279410). The number of spermatozoa released from cauda epididymes is dramatically reduced, and the spermatozoa are morphologically abnormal with greatly compromised motility (PubMed:23177736). Male mice display increased m6A in mRNAs in spermatocytes, leading to aberrant splicing and production of shorter transcripts that are rapidly degraded (PubMed:29279410). Belongs to the alkB family.