CRYSTALLIZATION AND PRELIMINARY CRYSTALLOGRAPHIC ANALYSIS OF THE RAS BINDING DOMAIN OF RALGDS, A GUANINE-NUCLEOTIDE DISSOCIATION STIMULATOROF THE RAL PROTEIN

The RalGDS is a guanine nucleotide dissociation stimulator which activ ates the Ral protein, a Ras-like small GTPase. The C-terminal domain o f the RalGDS (C-RalGDS) binds tightly to the effector loop of Ras sugg esting that the RalGDS may be a crossing point of two signal tranducti on pathways associated with the Ras and Ral proteins. C-RalGDS has bee n purified and crystallized in space group C2, with unit-cell dimensio ns a=108.8, b=30.7, c=51.3 Angstrom, beta=91.7 degrees at 277 K and a= 103.8, b=30.55, c=51.4 Angstrom, beta=94.9 degrees for data collected at 100 K. The crystals diffract to 1.8 Angstrom at a synchrotron radia tion source. To use the multiple-wavelength anomalous diffraction meth od for phasing, a selenomethionine derivative of the protein has also been crystallized.