Table 1.

Characteristics and functions of m6A enzymes in RNA metabolism

Category	Gene	Characteristics and functions	References
Writers	METTL3	Promotes formation of the methyltransferase complex, installs m6A on RNA, and catalyzes m6A modification	[14, 22, 25]
	METTL14	Catalyzes the methylation reaction, mediates protein–protein interaction, and helps METTL3 recognize the special RNA substrate	[22, 25]
	METTL16	A homologue of METTL3 Regulator of cellular SAM levels and methylator of U6 small nuclear RNA	[31, 32]
	WTAP	Contributes to the localization of METTL3-METTL14 heterodimer to the nuclear speckle Recruits target RNA for m6A modification Enhances the catalytic capacity of the writer	[26]
	RBM15/15B	Binds the m6A complex and recruit it to special RNA site	[27, 28]
	VIRMA	Recruits the m6A complex to a special RNA site where it interacts with polyadenylation cleavage factors CPSF5 and CPSF6	[30]
	ZC3H13	Bridges WTAP to the mRNA-binding factor to enhance m6A	[29]
Erasers	FTO	Reverses RNA modification and controls cellular homeostasis	[33, 35]
	ALKBH5	Maintains the balance of m6A levels within the transcriptome Contributions to in alkylated DNA repair	[34, 35]
	ALKBH3	Performs its demethylation function on tRNA rather than mRNA or rRNA Generally considered to serve as a DNA repair enzyme	[37]
Readers	YTH family	First five characterized m6A readers
	YTHDC1	Contributes to RNA splicing and export Plays a critical role in the pre-mRNA processing	[40]
	YTHDC2	Enhances the translation of target RNA but also reduces the abundance of target RNA	[41]
	YTHDF1	Enhances mRNA translation	[43]
	YTHDF2	Promotes mRNA degradation	[44]
	YTHDF3	Enhances translation and degradation by interacting with YTHDF1 and YTHDF2	[45]
	HNRNP family	Another group of RNA-binding proteins
	HNRNPA2B1	Mediates miRNA processing by recruiting a microprocessor complex upon binding to the m6A	[45, 47]
	HNRNPC/HNRNPG	Mediate selective splicing of m6A-modified transcripts, but do so through direct interaction whit m6A-dependent structural switches	[45]
	eIF3	Initiates the translation procedure by binding to the m6A site in the 5’-UTR of mRNA	[48]
	IGF2BPs	Stabilizes the target gene	[48]
	Prrc2a	Stabilizes mRNA expression by binding to a consensus GGACU motif in the coding sequence in an m6A-dependent manner	[49]