MUTAGENESIS OF HUMAN PROFILIN LOCATES ITS POLY(L-PROLINE)-BINDING SITE TO A HYDROPHOBIC PATCH OF AROMATIC-AMINO-ACIDS

The actin-binding protein, profilin, contains a src-homology (SH) 3-li ke fold (Schutt, C.E. et al., submitted), and its tight interaction wi th poly(L-proline) is reminiscent of the binding activity exhibited by SH3-domains. Here we demonstrate that replacements of aromatic amino acids in a hydrophobic patch on the surface of the profilin molecule a bolish its poly(L-proline)-binding capacity. However, the location of this hydrophobic patch is found in another region of the molecule than that displaying structural similarities with SH3 domains.