RalGDSRBD

RalGDSRBD refers to the Ras-binding domain found in Ral guanine nucleotide dissociation stimulator (RalGDS) and related proteins. This domain binds Ras when Ras is in its active, GTP-bound form, and it serves as the interface through which Ras signals are transmitted to the Ral GTPase family. By recognizing the switch I and II regions of Ras, the RalGDSRBD couples Ras activation to the Ral pathway, enabling the Ral guanine nucleotide dissociation stimulator proteins to regulate RalA and RalB activity.

The RalGDSRBD is typically located in the N-terminal region of RalGDS family proteins and is structurally related to Ras-binding domains found in other Ras effectors. It is highly conserved across eukaryotes, reflecting its fundamental role in transmitting signals from Ras to downstream targets. In humans and other vertebrates, RalGDS family members containing this domain link upstream Ras signaling to downstream Ral-mediated processes, such as vesicle trafficking and cytoskeletal organization, with outcomes that can influence cell migration and proliferation depending on context.

Biological significance of the RalGDSRBD lies in its ability to mediate specific protein–protein interactions that connect the Ras signaling axis to the Ral GTPase signaling cascade. Because proper regulation of Ras and Ral pathways is important for normal cellular function, disruptions in the Ras–RalGDSRBD interaction are of interest in studies of cancer biology and signal transduction. The domain exemplifies the modular organization of signaling proteins, where a conserved Ras-binding module interfaces with distinct downstream effector mechanisms.