Common and divergent peptide binding specificities of hsp70 molecular chaperones.

摘要: We have studied the binding of synthetic peptides to three hsp70 molecular chaperones, DnaK, BiP, and hsc70, as a model for interaction proteins with unfolded regions target polypeptides. measured ability 53 inhibit formation complexes between denatured lactalbumin. Peptides that bound highest affinity all contained stretches at least 7 residues included large hydrophobic basic amino acids, but few or no acidic residues. Amino acid substitutions within one heptameric peptide showed an important feature its chaperones was residue in position 4, while specificity differences were revealed by positions 2 6. Such frequently observed other peptides, most extreme example being rich high intermediate negligible BiP. Substitution lysine this tyrosine abolished difference increasing affinities DnaK hsc70 5- 20-fold, respectively, BiP greater than orders magnitude. Thus, can exhibit common exclusive specificities, depending on sequence.