Biological role of the two overlapping poly(A)-binding protein interacting motifs 2 (PAM2) of eukaryotic releasing factor eRF3 in mRNA decay

Schematic drawing of the translation termination-coupled regulation of the PAM2-containing deadenylase complexes by eRF3. (A) Competitive suppression of deadenylase activity by eRF3 binding to PABPC1. (B) Activation of PAM2-containing deadenylases through the dual interactions of PAM2–PABC and deadenylase–poly(A). (C) Possible role of the overlapping PAM2 motifs in eRF3. Upon the recruitment of one of the eRF3 molecules to the ribosome, relocation of eRF3 among the poly(A)-bound PABPC1 molecules would eventually allow a particular PABPC1 to become available for the dual deadenylase interactions, as shown in B.