m 6 A-modified RNAs possess distinct poly(A) tails.

N6-methyladenosine(m6A)has been found to be the most com-mon type of post-transcriptional chemical modification in mamma-lian mRNAs and long non-coding RNAs(lncRNAs)(Dominissini et al.,2012;Meyer et al.,2012).In both mammals and yeast,RNA m6A preferentially occurs in both gene coding regions and 3'untrans-lated regions(3'-UTRs),implicating its fundamental roles in every aspect of post-transcriptional regulation,including splicing,stability,and translation(Wang et al.,2014,2015;Zhao et al.,2014;Yang et al.,2018b).The poly(A)tails are non-templated homopolymeric se-quences at the 3'-ends of most mRNAs and lncRNAs.