Table 2.

The main components of methyladenosine modification systems^*.

MT	Writers	Erasers	Readers and its functions
m6A	METTL3/14, WTAP, KIAA1429 (VIRMA), RBM15/15B, ZC3H13, CBLL1, ZFP217, SMAD2/3, CEBPZ, METTL5, METTL16, ZCCHC4	FTO, ALKBH5	In nucleus	YTHDC1		Mediating splicing and nuclear export
				hnRNPA2/B1, hnRNPC and hnRNPG		Mediating splicing
			In cytoplasm	YTHDC2		Diversify
				YTHDF1 and METTL3		Facilitating translation
				YTHDF2		Facilitating decay
				YTHDF3		Work with YTHDF1 or YTHDF2
				IGF2BP1/2/3, FMRP, PRRC2A		Facilitating stability
m6Am	PCIF1 (CAPAM), METTL4	FTO	There is no m6Am reader that has been identified; and the functions of it still controversial (facilitating or preventing decay and translation)?
m1A	TRMT10C, TRMT6/61A, TRMT61B, BMT2, NML	FTO, ALKBH1, ALKBH3	YTHDF1		Facilitating translation
			YTHDF2/3		Promoting decay
			YTHDC1		Unclear

MT, modification types; writers, methyltransferases; erasers, demethylases; readers, the proteins that bind to methylation modifications; m⁶A, N⁶-methyladenosine; m⁶Am, N⁶,2’-O-dimethyladenosine; m¹A, N¹-methyladenosine; METTL3/5/14/16, methyltransferase-like3/5/14/15; WTAP, Wilms tumor 1-associated protein; RBM15/15B, RNA-binding motif protein 15/15B; ZC3H13, zinc finger CCCH-type containing 13; CBLL1, Cbl photo oncogene like 1; ZFP217, zinc finger protein 217; CEBPZ, CAATT-box binding protein; ZCCHC4, CCHC-type-containing 4; FTO, fat mass and obesity-associated protein; ALKBH1/3/5, AlkB homolog 1/3/5; YTHDC1/2, YT521-B homology (YTH) domain-containing protein 1/2; hnRNPA2/B1, heterogeneous nuclear ribonucleoprotein A2/B1; hnRNPC, heterogeneous nuclear ribonucleoprotein C; hnRNPG, heterogeneous nuclear ribonucleoprotein G; FMRP, fragile X mental retardation protein; PRRC2A, proline rich coiled-coil 2 A; PCIF1, phosphorylated CTD-interacting factor 1; TRMT10C/6/61A/61B, tRNA methyltransferase 10C/6/61A/61B; BMT2, base methyltransferase of 25S RNA; NML, nucleomethylin. *Has been identified at present.