Sb. Cantor et al., IDENTIFICATION AND CHARACTERIZATION OF RAL-BINDING PROTEIN-1, A POTENTIAL DOWNSTREAM TARGET OF RAL GTPASES, Molecular and cellular biology, 15(8), 1995, pp. 4578-4584
Ral proteins constitute a distinct family of Ras-related GTPases, Alth
ough similar to Ras in amino acid sequence, Ral proteins are activated
by a unique nucleotide exchange factor and inactivated by a distinct
GTPase-activating protein, Unlike Ras, they fail to promote transforme
d foci when activated versions are expressed in cells, To identify dow
nstream targets that might mediate a Ral-specific function, we used a
Saccharomyces cerevisiae-based interaction assay to clone a novel cDNA
that encodes a Ral-binding protein (RalBP1), RalBP1 binds specificall
y to the active GTP-bound form of RalA and not to a mutant Ral with a
point mutation in its putative effector domain, In addition to a Ral-b
inding domain, RalBP1 also contains a Rho-GTPase-activating protein do
main that interacts preferentially with Rho family member CDC42, Since
CDC42 has been implicated in bud site selection in S. cerevisiae and
filopodium formation in mammalian cells, Ral may function to modulate
the actin cytoskeleton through its interactions with RalBP1.