<prompt> All are the processing reaction in tRNA, except:CCA tailingMethylation of basesPoly A tailingTrimming of 5 end  <response>: Post-transcriptional modification of tRNA precursor:Standard bases A, U, G, C undergo methylation, reduction, deamination, rearranged glycosidic bond.Cleavage and attachment of CCA terminal at 3 end takes place in cytoplasm.Methylation of tRNA takes place in nucleus.Note:- Poly A tailing is a processing step of mRNA primary transcript.Reference- Harper 30th edition 