Poly(A) polymerase (PAP)

Poly(A) polymerase is an essential enzyme responsible for catalyzing the addition of adenosine monophosphate residues to the 3' end of eukaryotic pre-messenger RNA, forming the poly(A) tail. This process, known as polyadenylation, is critical for proper maturation, export, stability, and translation efficiency of messenger RNAs. The canonical form in mammals is called PAPα. Structurally, it belongs to the DNA polymerase beta superfamily and contains three main domains: an N-terminal catalytic domain homologous to other nucleotidyl transferases ("palm" domain), a middle domain functionally analogous to "fingers" domains in template-directed polymerases, and a C-terminal region involved in protein-protein interactions[1][9]. The enzyme operates within large multi-protein complexes that coordinate cleavage at specific sites on pre-mRNAs before adding the poly(A) tail[9]. Multiple isoforms exist with specialized roles in different cellular compartments or developmental stages. While crucial for cell viability and gene expression control[2][4], there are currently no approved drugs targeting this enzyme directly. **Note:** The query "Poly polymerase" appears ambiguous or incorrect—there are two distinct enzymes commonly confused due to similar names: 1. **Poly(A) Polymerase** – Adds adenine tails during RNA processing. 2. **Poly(ADP-ribose) Polymerase (PARP)** – A DNA repair enzyme targeted by several cancer drugs[6]. If you intended "PARP," please clarify; otherwise this entry refers specifically to *poly(A) polymerase*, which does not have current direct pharmacological targeting but plays fundamental roles in post-transcriptional gene regulation[1][2][9].

Other names

Polyadenylate polymerasePolyadenylation polymerasePAPαStar-PAPhGLD2