GBF1
Description
The GBF1 (golgi brefeldin A resistant guanine nucleotide exchange factor 1) is a protein-coding gene located on chromosome 10.
Golgi-specific brefeldin A-resistance guanine nucleotide exchange factor 1 is a protein that in humans is encoded by the GBF1 gene.
GBF1 is a guanine nucleotide exchange factor (GEF) that activates members of the Arf family of small GTPases. These GTPases are essential for trafficking in the early secretory pathway. GBF1's GEF activity starts the coating of new vesicles by activating ARFs. This happens through replacing GDP with GTP, which changes the shape of the ARF protein. GBF1 is located on the cis-Golgi membranes and its localization is influenced by the Arf protein. GBF1 is involved in the recruitment of the COPI coat complex to the ER exit sites (ERES), and the endoplasmic reticulum-Golgi intermediate (ERGIC) and cis-Golgi compartments. This process requires ARF1 activation. GBF1 is also involved in retrograde transport from the ERGIC and cis-Golgi compartments back to the endoplasmic reticulum (ER) via COPI vesicles. In addition to COPI vesicles, GBF1 is involved in the recruitment of proteins like GGA1, GGA2, GGA3, BIG1, BIG2, and the AP-1 adaptor protein complex to the trans-Golgi network. These proteins are important for chlathrin-dependent transport. This function also depends on GBF1's GEF activity, likely towards ARF4 and ARF5. GBF1 also has GEF activity towards ARF1 and ARF5. GBF1 has been linked to the processing of PSAP and is required for the assembly of the Golgi apparatus. When phosphorylated by AMPK, GBF1 plays a role in Golgi disassembly during mitosis and under stress conditions. While there is some debate, GBF1 may also be involved in the recruitment of PNPLA2 to lipid droplets via COPI vesicles. In neutrophils, GBF1 is involved in G protein-coupled receptor (GPCR)-mediated chemotaxis and superoxide production. GBF1 is recruited to the leading edge of neutrophils by phosphatidylinositol-phosphates generated upon GPCR stimulation. This recruitment allows GBF1 to activate ARF1 and recruit GIT2 and the NADPH oxidase complex. GBF1 is also important for maintaining mitochondrial morphology. GBF1 can form homodimers and probably homotetramers. It interacts with COPG1, ARF1, ARF3, ARF4, ARF5, RAB1B (GTP-bound form), GGA1, GGA2, GGA3, USO1, PNPLA2, and ARMH3. It also interacts with poliovirus protein 3A.
GBF1 is also known as ARF1GEF, CMT2GG, CMTDI2, CMTDIA.
