Characterization of the proline-rich region of mouse MAPKAP kinase 2: influence on catalytic properties and binding to the c-abl SH3 domain in vitro.

The primary structure of mouse MAP kinase-activated protein (MAPKAP) kinase 2 contains a proline-rich N-terminal region which might function as a src-homology 3 (SH3) domain-binding motif in vivo. To demonstrate the ability of this region to bind SH3 domains, we analyzed the interaction of the SH3 domain of the protein tyrosine kinase c-abl with MAPKAP kinase 2. It is demonstrated, that the proline-rich region specifically binds c-abl-SH3 domain in vitro. Furthermore, it is shown, that deletion of this proline-rich region does not significantly influence the substrate binding properties of the enzyme when analyzed with the substrate small heat shock protein Hsp25. The data suggest that the proline-rich region of MAPKAP kinase 2 could interact with proteins containing SH3-domains also in vivo regulating its cellular localization and/or modulating its enzymatic properties.