RabGAP1 (also known as GAPCenA) is a GTPase activating protein that targets Rab6 []and binds Rab36 []. It is is mainly cytosolic but that a minor pool is associated with the centrosome []. GAPCenA consists of an N-terminal phosphotyrosine binding (PTB) domain, a central TBC domain, and a C-terminal CC domain. It binds Rab36 via the N-terminal PTB domain []. It is involved in the metaphase/anaphase transition [].
The RH2 (RILP homology 2) Rab-binding domain is found in the following animalproteins [, , ]:Rab interacting lysosomal proteins (RILP), which interacts with Rab7,Rab34, and Rab36.RILP-like 1 (RILP-L1), which interacts with Rab12, Rab34, and Rab36.RILP-like 2 (RILP-L2), which interacts with Rab34 and Rab36.JNK-interacting protein 3 (JIP3), which interacts with Rab36 alone.JNK-interacting protein 4 (JIP4), which interacts with Rab36 alone.The RH2 domain is folded into a long helix alpha1 and a short helix alpha2connected by a very tight loop. The RH2 domain forms atightly associated four helices homodimer in which both helices alpha1 andalpha2 are involved in dimerization. Such a homodimer binds to two separateRab-GTP molecules on opposite sides, with both helices involved in theinteraction with Rab. In the complex interface, although each Rab-GTPinteracts with both helices of the RH2 domain, these two helices arecontributed by two different molecules, with helix alpha1 coming from oneprotomer and helix alpha2 from the other protomer [].The entry represents the entire RH2 domain.
