GTP-binding protein regulators

Initiation factor 2 (IF2) guides the ribosome to the elongation phase of protein synthesis. Here, Basu et al. provide structural insights into how compact IF2-GDP makes way for initiator tRNA accommodation into the peptidyl (P) site of the ribosome.

The orphan GPR158 receptor belongs to the class C GPCR family and interacts with the regulator of G protein signaling 7 (RGS7)-Gβ5 complex. Here, the authors present the cryo-EM structure of human GPR158, which reveals that the extracellular domain contains a PAS domain, and they also determine the structures of GPR158 in complex with either one or two RGS7-Gβ5 heterodimers and discuss implications for the signaling mechanism.

Interface mutations in the GTPase switch protein Gsp1 (the yeast homologue of human RAN) allosterically affect the kinetics of the switch cycle, revealing a systems-level mechanism of multi-specificity.

Here the authors reveal unique structural organization of the mammalian TRAPPII complex, which is critical in regulating membrane trafficking. They find that TRAPPII serves as a guanine nucleotide exchange factor for unexpected Rab GTPases such as Rab43 and Rab19.

The bacterial defense system McrBC is a two-component motor-driven nuclease complex that cleaves foreign DNA. Here, the authors present the structures of the GTP-specific AAA + motor protein McrB and two McrBC complexes and discuss the molecular mechanism of how McrC binding stimulates McrB GTP hydrolysis.