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Structural basis of ligand recognition by PABC, a highly specific peptide-binding domain found in poly(A)-binding protein and a HECT ubiquitin ligase.

The C-terminal domain of poly(A)-binding protein (PABC) is a peptide-binding domain found in poly(A)-binding proteins (PABPs) and a HECT (homologous to E6-AP C-terminus) family E3 ubiquitin ligase. In protein synthesis, the PABC domain of PABP functions to recruit several translation factors possessing the PABP-interacting motif 2 (PAM2) to the mRNA poly(A) tail. We have determined the solution structure of the human PABC domain in complex with two peptides from PABP-interacting protein-1 (Paip1) and Paip2. The structures show a novel mode of peptide recognition, in which the peptide binds as a pair of beta-turns with extensive hydrophobic, electrostatic and aromatic stacking interactions. Mutagenesis of PABC and peptide residues was used to identify key protein-peptide interactions and quantified by isothermal calorimetry, surface plasmon resonance and GST pull-down assays. The results provide insight into the specificity of PABC in mediating PABP-protein interactions.

Pubmed ID: 14685257


  • Kozlov G
  • De Crescenzo G
  • Lim NS
  • Siddiqui N
  • Fantus D
  • Kahvejian A
  • Trempe JF
  • Elias D
  • Ekiel I
  • Sonenberg N
  • O'Connor-McCourt M
  • Gehring K


The EMBO journal

Publication Data

January 28, 2004

Associated Grants

  • Agency: NIGMS NIH HHS, Id: 1R01 GM66157-01

Mesh Terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Binding Sites
  • Carrier Proteins
  • Conserved Sequence
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Ligands
  • Models, Molecular
  • Molecular Sequence Data
  • Nuclear Magnetic Resonance, Biomolecular
  • Peptide Initiation Factors
  • Peptides
  • Poly(A)-Binding Proteins
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Tertiary
  • RNA-Binding Proteins
  • Repressor Proteins
  • Ribosomal Proteins
  • Static Electricity
  • Ubiquitin-Protein Ligases