Non-canonical poly(A) polymerases
non-canonical poly(a) polymerases
Polyadenylation of mitochondrial RNAs in higher eukaryotic organisms have diverse effects on their function and metabolism. Polyadenylation completes the UAA stop codon of a majority of mitochondrial mRNAs in mammals, regulates the translation of the mRNAs, and has diverse effects on their stability.    The addition of a poly(A) tail is catalyzed by poly(A) polymerases (PAPs). Nuclear PAPs that are involved in the 3′-end processing of pre-mRNAs have been studied extensively over the years. More recently, a collection of non-canonical PAPs (ncPAPs) has been identified, which are involved in polyadenylation in other organelles (as well as in the nucleus). Some of these ncPAPs have relaxed base selectivity and can also synthesize oligo- or poly-uridylate tails, and hence are also known as poly(U) polymerases (PUPs) or terminal uridylate transferases (TUTs or TUTases).