Poly(A) Polymerase catalyzes the incorporation of adenine residues into the 3' termini of RNA, effectively adding a poly(A) tail to RNA. The enzyme uses single-stranded RNA as a primer during poly(A) tailing. Poly(A) Polymerase is supplied in a buffer of 25 mM Tris-HCl (pH 7.9), 500 mM NaCl, 1 mM EDTA, 0.1 mM DTT, and 50% glycerol.