Heterogenous nuclear RNA ($hn\$RNA) undergo two additional processing known as capping and tailing. In capping an unusual nucleotide (methyl guanosine triphosphate) is added to the 5’ end of hnRNA. In tailing, adenylate residues (200-300) are added a 3’ end in template independent manner. In splicing, introns are removed and exons are joined in a definite order.