The CCA-adding enzyme (ATP:tRNA adenylyltransferase or CTP:tRNA cytidylyltransferase (EC )) generates the conserved CCA sequence responsible for the attachment of amino acid at the 3' terminus of tRNA molecules.
3. The increased activity of tRNA methylases was not due to the presence in the extracts of stimulatory or inhibitory molecules of low molecular weight such as polyamines or S-adenosylhomocysteine. 4. Other enzymes concerned with tRNA metabolism (RNA polymerase, ATP-tRNA adenylyltransferase, aminoacyl-tRNA ligases) were also increased in activity in the tumour tissue.