human RAS and EF hand domain containing [Homo sapiens]

Rab proteins constitute the largest branch of the Ras GTPase superfamily. Rabs use the guanine nucleotide-dependent switch mechanism to regulate each of the four major steps in membrane traffic: vesicle budding, delivery, tethering, and fusion. Rasef belongs to the Rab subfamily and contains two domains: Ras and EF hand calcium binding. Its function is unknown and the structure of Rasef will provide basis for understanding its potential functions. Here, we solved the structure of the Rab domain of Rasef at 2.15 Å. The overall structure of the Rab domain is similar to previous Rabs. Briefly, the structure consists of a core formed by a six stranded β-sheet surrounded by five α-helices. The conserved phosphate-binding loop (P-loop) motif in this structure is 548-GDAAVGKS-555, with bound GDP. The switch II region (Q600 – A612) is visible but the switch I region (K563 – Q567) is disordered. We predict that the switch regions and some distinct surface area play crucial roles for the recognition by specific effector molecules.