HEN1 (HUA ENHANCER 1) is a methyltransferase that can methylate 3'-end of miRNAs, siRNas and trans-acting small interfering RNAs (ta-siRNAs). This protein protects the 3'-end of sRNAs from uridylation activity and degradation by adding a methyl group to the ribose of the last nucleotide of sRNAs.Alternative protein names: Small RNA 2'-O-methyltransferase, Protein CORYMBOSA 2, S-adenosylmethionine-dependent RNA methyltransferase HEN1.