Poly A Binding Protein Interacting Protein 2 (PAIP2)

By Far Western interaction cloning using human PABP as the probe and a placenta cDNA expression library, Khaleghpour et al. (2001) isolated a 1.4-kb cDNA encoding PAIP2. The highly acidic (predicted pI of 3.9), 127-amino acid protein has a predicted molecular mass of 14.5 kD and acts as a repressor of translation both in vitro and in vivo.

PAIP2 preferentially inhibited translation of a poly(A)-containing mRNA but had no effect on the translation of hepatitis C virus mRNA, which is cap and eIF4G independent. The authors showed that PAIP2 decreases the affinity of PABP for poly(A) RNA and disrupts the repeating structure of poly(A) ribonucleoprotein. Furthermore, PAIP2 was found to compete with PAIP1 (605184) for PABP binding.