THE GTPASE DYNAMIN BINDS TO AND IS ACTIVATED BY A SUBSET OF SH3 DOMAINS

Src homology 3 (SH3) domains have been implicated in mediating protein -protein interactions in receptor signaling processes; however, the pr ecise role of this domain remains unclear. In this report, affinity pu rification techniques were used to identity the GTPase dynamin as an S H3 domain-binding protein. Selective binding to a subset of 15 differe nt recombinant SH3 domains occurs through proline-rich sequence motifs similar to those that mediate the interaction of the SH3 domains of G rb2 and Abl proteins to the guanine nucleotide exchange protein, Sos, and to the 3BP1 protein, respectively. Dynamin GTPase activity is stim ulated by several of the bound SH3 domains, suggesting that the functi on of the SH3 module is not restricted to protein-protein interactions but may also include the interactive regulation of GTP-binding protei ns.