GGAs: A Family of ADP Ribosylation Factor-binding Proteins Related to Adaptors and Associated with the Golgi Complex (original) (raw)

The Arf GAPs AGAP1 and AGAP2 distinguish between the adaptor protein complexes AP1 and AP3

Journal of Cell Science, 2005

ADP ribosylation factors (Arf) regulate membrane trafficking at multiple intracellular sites by recruiting coat proteins to membranes. The site-specific regulation of Arf is thought to be mediated by regulatory proteins including the guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). Here, we test this hypothesis by comparing the site of action of the Arf GAP AGAP2 to the closely

GBF1, a cis-Golgi and VTCs-localized ARF-GEF, is implicated in ER-to-Golgi protein traffic

Journal of Cell Science, 2006

The formation and maturation of membrane carriers that transport cargo from the ER to the Golgi complex involves the sequential action of the coat protein complexes COPII and COPI. Recruitment of COPI to nascent carriers requires activation of ADP-ribosylation factors by a BrefeldinA-sensitive guanine nucleotide exchange factor. Using new antisera and a GFP-tagged protein, we demonstrate that the exchange factor GBF1 localized to both Golgi membranes and peripheral puncta, near but separate from ER exit sites. Live cell imaging revealed that GFP-GBF1 associates dynamically with both membranes through rapid exchange with a large cytosolic pool. Treatment with BrefeldinA dramatically altered this rapid exchange, causing accumulation of GBF1 on both Golgi and peripheral puncta before eventual redistribution to the ER in a microtubule-dependent manner. Measurement of diffusion coefficients and subcellular fractionation confirmed this shift in GBF1 from cytosolic to membrane bound. Brefe...