Ras GTPase-activating protein-binding protein (also known as GAP SH3 domain-binding protein, G3BP) is involved in several cellular functions and is implicated in stress granule assembly RNA metabolism and hereby cell motility, nuclear transportation and NFkappaB, Ras and Wnt signaling [, ]. There are three human isoforms of G3BP: G3BP1, G3BP2a and G3BP2b. The main difference between the variants is found in the number of PxxP motifs in the central region of the protein []. G3BP contains the PxxP motifs, the glutamine- and glycine rich regions, an RNA recognition motif (RRM) and an N-terminal NTF2-like domain. The NTF2-like domain is the most highly conserved part of the G3BP sequence and it has been implicated in several G3BP functions []. This entry represents G3BP2, which is a cytoplasmic protein that interacts with both IkappaBalpha and IkappaBalpha/NF-kappaB complexes, indicating that G3BP2 may play a role in the control of nucleocytoplasmic distribution of IkappaBalpha and cytoplasmic anchoring of the IkappaBalpha/NF-kappaB complex []. It also contributes to stress granule formation [].
This entry represents the RNA recognition motif (RRM) of G3BP2, a cytoplasmic protein that interacts with both IkappaBalpha and IkappaBalpha/NF-kappaB complexes, indicating that G3BP2 may play a role in the control of nucleocytoplasmic distribution of IkappaBalpha and cytoplasmic anchoring of the IkappaBalpha/NF-kappaB complex []. It also contributes to stress granule formation []. G3BP2 contains an N-terminal nuclear transfer factor 2 (NTF2)-like domain, an acidic domain, a domain containing five PXXP motifs, an RNA recognition motif (RRM domain), and an Arg-Gly-rich region (RGG-rich region, or arginine methylation motif). It binds to the SH3 domain of RasGAP, a multi-functional protein controlling Ras activity, through its N-terminal NTF2-like domain []. The acidic domain is sufficient for the interaction of G3BP2 with the IkappaBalpha cytoplasmic retention sequence. Furthermore, G3BP2 might influence stability or translational efficiency of particular mRNAs by binding to RNA-containing structures within the cytoplasm through its RNA-binding domain [].
