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

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.
Mesh Terms:
Amino Acid Motifs, Amino Acid Sequence, Animals, Binding Sites, Calreticulin, Cells, Cultured, Immunohistochemistry, Ligands, Microtubule-Associated Proteins, Models, Molecular, Molecular Sequence Data, Peptide Fragments, Peptide Library, Rats, Surface Plasmon Resonance
FEBS J.
Date: Nov. 01, 2007
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