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Paip1 interacts with poly(A) binding protein through two independent binding motifs
Guylaine Roy1, Gregory De Crescenzo, Kianoush Khaleghpour
1Department of Biochemistry and McGill Cancer Centre, McGill University, Montréal, Québec, Canada H3G 1Y6.
Molecular and Cellular Biology
|May 9, 2002
Summary
Poly(A)-binding protein (PABP) circularizes mRNA via interactions with eIF4G, enhancing translation. Paip1 protein binds PABP at two sites, with high affinity, regulating PABP activity.
Area of Science:
- Molecular Biology
- Biochemistry
- Gene Expression Regulation
Background:
- The 3' poly(A) tail of eukaryotic messenger RNAs (mRNAs) is crucial for translation regulation.
- Poly(A)-binding protein (PABP) interacts with eukaryotic initiation factor 4G (eIF4G) to circularize mRNA, enhancing translation.
- PABP activity is modulated by interacting proteins Paip1 and Paip2.
Purpose of the Study:
- To elucidate the interaction mechanism between Paip1 and PABP.
- To identify the specific binding sites and affinity of the Paip1-PABP interaction.
Main Methods:
- Far-Western blotting
- Glutathione S-transferase (GST) pull-down assays
- Surface plasmon resonance (SPR) analysis
Main Results:
- Paip1 possesses two distinct PABP-binding sites: PAM1 (C-terminal acidic region) and PAM2 (N-terminal 15-amino acid stretch).
- PABP exhibits two Paip1 binding sites: one within RNA recognition motifs 1 and 2, and another in the C-terminal domain.
- Paip1 binds PABP with 1:1 stoichiometry and a high affinity (apparent K(d) of 1.9 nM).
Conclusions:
- The detailed characterization of the Paip1-PABP interaction provides insights into the regulation of mRNA translation.
- Understanding these molecular interactions is key to comprehending eukaryotic gene expression control.