Identification of calreticulin as a ligand of GABARAP by phage display screening of a peptide library

FEBS J. 2007 Nov;274(21):5543-55. doi: 10.1111/j.1742-4658.2007.06073.x. Epub 2007 Oct 4.


4-Aminobutyrate type A (GABA(A)) receptor-associated protein (GABARAP) is a ubiquitin-like modifier implicated in the intracellular trafficking of GABA(A) receptors, and belongs to a family of proteins involved in intracellular vesicular transport processes, such as autophagy and intra-Golgi transport. In this article, it is demonstrated that calreticulin is a high affinity ligand of GABARAP. Calreticulin, although best known for its functions as a Ca(2+) -dependent chaperone and a Ca(2+) -buffering protein in the endoplasmic reticulum, is also localized to the cytosol and exerts a variety of extra-endoplasmic reticulum functions. By phage display screening of a randomized peptide library, peptides that specifically bind GABARAP were identified. Their amino acid sequences allowed us to identify calreticulin as a potential GABARAP binding protein. GABARAP binding to calreticulin was confirmed by pull-down experiments with brain lysate and colocalization studies in N2a cells. Calreticulin and GABARAP interact with a dissociation constant K(d) = 64 nm and a mean lifetime of the complex of 20 min. Thus, the interaction between GABARAP and calreticulin is the strongest so far reported for each protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Calreticulin / chemistry*
  • Calreticulin / metabolism
  • Cells, Cultured
  • Immunohistochemistry
  • Ligands
  • Microtubule-Associated Proteins / chemistry*
  • Microtubule-Associated Proteins / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Peptide Library
  • Rats
  • Surface Plasmon Resonance


  • Calreticulin
  • GABARAP protein, rat
  • Ligands
  • Microtubule-Associated Proteins
  • Peptide Fragments
  • Peptide Library