A PROTEIN PHOSPHATASE-1-BINDING MOTIF IDENTIFIED BY THE PANNING OF A RANDOM PEPTIDE DISPLAY LIBRARY

An unusually large number of regulatory or targeting proteins that bin d to the catalytic subunit of protein phosphatase-1 have been recently reported. This can be explained by their possession of a common prote in motif that interacts with a binding site on protein phosphatase-1. The existence of such a motif was established by the panning of a rand om peptide library in which peptide sequences are displayed on the Esc herichia coli bacterial flagellin protein for bacteria that bound to p rotein phosphatase-1. There were 79 isolates containing 46 unique sequ ences with the conserved motif VXF or VXW, where X was most frequently His or Arg. In addition, this sequence was commonly preceded by 2-5 b asic residues and followed by 1 acidic residue. This study demonstrate s that binding to protein phosphatase-1 can be conferred to a protein by the presentation of a peptide motif on a surface loop. This binding motif is found in a number of protein phosphatase-1-binding proteins.