Paip1 interacts with poly(A) binding protein through two independent binding motifs.
The 3' poly(A) tail of eukaryotic mRNAs plays an important role in the regulation of translation. The poly(A) binding protein (PABP) interacts with eukaryotic initiation factor 4G (eIF4G), a component of the eIF4F complex, which binds to the 5' cap structure. The PABP-eIF4G interaction brings about the circularization of the mRNA by joining its 5' and 3' termini, thereby stimulating mRNA translation. The activity of PABP is regulated by two interacting proteins, Paip1 and Paip2. To study the mechanism of the Paip1-PABP interaction, far-Western, glutathione S-transferase pull-down, and surface plasmon resonance experiments were performed. Paip1 contains two binding sites for PABP, PAM1 and PAM2 (for PABP-interacting motifs 1 and 2). PAM2 consists of a 15-amino-acid stretch residing in the N terminus, and PAM1 encompasses a larger C-terminal acidic-amino-acid-rich region. PABP also contains two Paip1 binding sites, one located in RNA recognition motifs 1 and 2 and the other located in the C-terminal domain. Paip1 binds to PABP with a 1:1 stoichiometry and an apparent K(d) of 1.9 nM.
Roy
Guylaine
G
Department of Biochemistry and McGill Cancer Centre, McGill University, Montréal, Québec, Canada H3G 1Y6.
De Crescenzo
Gregory
G
Khaleghpour
Kianoush
K
Kahvejian
Avak
A
O'Connor-McCourt
Maureen
M
Sonenberg
Nahum
N
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D015153:Blotting, Western; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D008954:Models, Biological; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D039102:Poly(A)-Binding Proteins; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020349:Surface Plasmon Resonance
C111580:PAIP1 protein, human; D010448:Peptide Initiation Factors; D039102:Poly(A)-Binding Proteins; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins