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 G3BP1, which has been identified as a phosphorylation-dependent endoribonuclease that interacts with the SH3 domain of RasGAP []. However, this interaction has been questioned []. G3BP1 binds to and cleaves the 3'-untranslated region (3'-UTR) of the c-myc mRNA in a phosphorylation-dependent manner []. G3BP1 has been linked to the formation of stress granules (SGs), membrane-less structures consisting of mRNA and protein aggregates form rapidly in response to a wide range of stresses and viral infections [, ]. G3BP1 is targeted by many viruses and may be involved in innate immune response [, ]. Its activities can be regulated through post-translational modifications [].
This entry represents the RNA recognition motif (RRM) of G3BP1, which has been identified as a phosphorylation-dependent endoribonuclease that interacts with the SH3 domain of RasGAP []. However, this interaction has been questioned []. G3BP1 binds to and cleaves the 3'-untranslated region (3'-UTR) of the c-myc mRNA in a phosphorylation-dependent manner []. G3BP1 has been linked to the formation of stress granules (SGs), membrane-less structures consisting of mRNA and protein aggregates form rapidly in response to a wide range of stresses and viral infections [, ]. G3BP1 is targeted by many viruses and may be involved in innate immune response [, ]. Its activities can be regulated through post-translational modifications [].It has also been shown that G3BP1 is a novel Dishevelled-associated protein that is methylated upon Wnt3a stimulation and that arginine methylation of G3BP1 regulates both Ctnnb1 mRNA and canonical Wnt/beta-catenin signaling []. Furthermore, G3BP1 can be associated with the 3'-UTR of beta-F1 mRNA in cytoplasmic RNA-granules, demonstrating that G3BP1 may specifically repress the translation of the transcript [].G3BP1 contains an N-terminal nuclear transfer factor 2 (NTF2)-like domain, an RNA recognition motif (RRM domain), and an Arg-Gly-rich region (RGG-rich region, or arginine methylation motif). The RRM domain and RGG-rich region are canonically associated with RNA binding [].
