RanBP proteins form a heterogeneous family of proteins involved in nuclear transport. Among them, some contain a common region (RanBD1) involved in the binding of Ran, a Ras-related GTPase (see <PDOC00859>). This domain binds RanGTP and increases the rate of RanGAP1-induced GTP hydrolysis. RanBD1 displays some similarity with the WASP domain [1,2].

The crystal structure of RanBD1 of the human protein RanBP2 complexed with Ran, bound to a non-hydrolysable GTP analogue, has been resolved (see <PDB:1RRP>) [3]. Like the WASP domain, RanBD1 show a PH domain fold (see <PDOC50003>), although there is no detectable sequence similarity. Ran-GTP contacts RanBD1 in four different points, "embracing" RanBD1. This conformation can stabilize the binding of GTP to Ran.

The following proteins contain a RanBD1 domain:

• Mammalian Ran binding protein 1. RanBP1 is a small cytosolic protein, essential for nuclear import and export of RNA.
• Mammalian Ran binding protein 2. RanBP2 is a filamentous protein located in the Nuclear Pore Complex (NPC) on the cytoplasmic side of the ring. It could function in coupling RanGTP hydrolysis to NPC translocation through its Ran binding domain.
• Mammalian Ran binding protein 3 proteins. RanBP3 is localized in the nucleus and preferentially bind RanGTP and may be nuclear effectors of the Ran pathway.
• Yeast nucleoporin 2 (NUP2). NUP2 is a component of the nuclear pore complex. It may be involved in binding and translocation of proteins during nucleocytoplasmic transport.
• Mammalian nucleoporin NUP50.

The profile we developed covers the entire RanBD1 domain.