Specificity and expression of RalGPS as RalGEFs.

Ral proteins regulate a variety of biological processes and are major downstream targets of Ras because of association of the RalGDS family of exchange factors with Ras-GTP. However, a second, less-characterized family of Ral GEFs has also been isolated. Described here are methods used to determine the substrate specificity of this RalGPS family of GEFs, measure their membrane localization, interactions of with SH3 domains and phospholipids, as well as to measure their ability to activate Ral in vivo.