Golgi-specific brefeldin A-resistance guanine nucleotide exchange factor 1 (GBF1)

Guanine-nucleotide exchange factor (GEF) for members of the Arf family of small GTPases involved in trafficking in the early secretory pathway; its GEF activity initiates the coating of nascent vesicles through the localized production of activated ARFs through replacement of GDP with GTP. Recruitment to cis-Golgi membranes requires membrane association of Arf-GDP and may be regulated by ARF1, ARF3, ARF4 and ARF5.

Involved in COPI vesicle-dependent retrograde transport from the ERGIC and cis-Golgi compartments into the endoplasmic reticulum (ER) (PubMed:16926190, PubMed:17956946, PubMed:18003980, PubMed:12047556, PubMed:12808027, PubMed:19039328, PubMed:24213530). Involved in the trans-Golgi network recruitment of GGA1, GGA2, GGA3, BIG1, BIG2, and the AP-1 adaptor protein complex related to chlathrin-dependent transport; the purpose requires its GEF activity (likely at least in part on ARF4 and ARF5) (PubMed:23386609).