Ras-binding domain of Ras effectors (RBD)

The Ras-binding domain (RBD) is a conserved structural motif found in various downstream effector proteins of the Ras small GTPase family, including RAF kinases (ARAF, BRAF, CRAF), Phosphoinositide 3-kinase (PI3K), and RalGDS [1, 3]. This domain is responsible for the direct physical interaction with active, GTP-bound Ras, acting as a critical molecular switch that initiates signaling cascades governing cell proliferation, survival, and differentiation [4, 11]. In many human cancers, mutations in Ras (e.g., KRAS, NRAS) or its effectors (e.g., PIK3CA) lead to constitutive activation of these pathways, driving tumor growth and resistance to therapy [5, 8]. Therapeutic strategies targeting the RBD aim to disrupt these essential protein-protein interactions, effectively uncoupling oncogenic Ras from its downstream signaling machinery [6, 10]. Drugs such as rigosertib function as Ras-mimetics that bind to the RBDs of multiple effectors, while newer agents like BBO-10203 are designed to selectively and covalently inhibit the RBD of specific isoforms like PI3Kα [1, 13]. By targeting the interaction interface rather than the catalytic site, these inhibitors may offer improved selectivity and reduced toxicity compared to traditional kinase inhibitors [12, 13]. Consequently, the RBD represents a high-value target for the development of precision medicines in Ras-driven malignancies [6, 10].

Other names

Ras-binding domainPI3K RBDRAF RBDRas-effector interaction interfaceRas-associating domain

Inhibition of Ras-effector protein-protein interaction by binding to the Ras-binding domain (RBD) of effector proteins such as PI3K and RAF.