Taxonomic distribution of proteins containing Ras_bdg_2 domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing Ras_bdg_2 domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

The Ras-Byr2RBD complex: structural basis for Ras effector recognition in yeast.

Scheffzek K, Grunewald P, Wohlgemuth S, Kabsch W, Tu H, Wigler M, Wittinghofer A, Herrmann C
Structure. 2001; 9: 1043-50

BACKGROUND: The small GTP binding protein Ras has important roles in cellulargrowth and differentiation. Mutant Ras is permanently active and contributes tocancer development. In its activated form, Ras interacts with effector proteins, frequently initiating a kinase cascade. In the lower eukaryoticSchizosaccharomyces pombe, Byr2 kinase represents a Ras target that in terms ofsignal-transduction hierarchy can be considered a homolog of mammalianRaf-kinase. The activation mechanism of protein kinases by Ras is not understood,and there is no detailed structural information about Ras binding domains (RBDs) in nonmammalian organisms. RESULTS: The crystal structure of the Ras-Byr2RBDcomplex at 3 A resolution shows a complex architecture similar to that observedin mammalian homologous systems, with an interprotein beta sheet stabilized bypredominantly polar interactions between the interacting components. TheC-terminal half of the Ras switch I region contains most of the contact anchors, while on the Byr2 side, a number of residues from topologically distinct regions are involved in complex stabilization. A C-terminal helical segment, which is notpresent in the known mammalian homologous systems and which is part of theauto-inhibitory region, has an additional binding site outside the switch Iregion. CONCLUSIONS: The structure of the Ras-Byr2 complex confirms the Rasbinding module as a communication element mediating Ras-effector interactions;the Ras-Byr2 complex is also conserved in a lower eukaryotic system like yeast,which is in contrast to other small GTPase families. The extra helical segmentmight be involved in kinase activation.