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

Zhao, Xinhua; Claude, Alejandro; Chun, Justin; Shields, David J.; Presley, John F.; Melançon, Paul

doi:10.1242/jcs.03173

Cited by 96 publications

(119 citation statements)

References 70 publications

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“…GBF1 is critical for biogenesis of the Golgi ribbon in mammalian cells 10,13,25,[54][55][56] and for recruitment of the COPI coat that mediates protein traffic at the ER-Golgi interface and of the AP-1 and GGA adaptors that function at the TGN. 10,11,13,25,57 The architecture of the Golgi differs in mammalian and Drosophila cells and the Golgi ribbon found in mammalian cells is replaced by scattered but still polarized Golgi mini-stacks in Drosophila cells.…”

Section: Discussionmentioning

confidence: 99%

The Garz Sec7 domain guanine nucleotide exchange factor for Arf regulates salivary gland development in Drosophila

Szul¹,

Burgess

Jeon

et al. 2011

Cellular Logistics

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Section: Discussionmentioning

confidence: 99%

The Garz Sec7 domain guanine nucleotide exchange factor for Arf regulates salivary gland development in Drosophila

Szul¹,

Burgess

Jeon

et al. 2011

Cellular Logistics

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“…GBF1-mediated ARF activation is essential for the recruitment of the heptameric COPI coat to the Golgi and the ERGolgi intermediate compartment (9,17,22). Expression of GFP-GBF1 had no detectable effect on COPI recruitment as assessed by the localization of ␤-COP (supplemental Fig.…”

Section: Analysis Of 30 Cells Expressing Gfp-gbf1mentioning

confidence: 95%

“…Golgi Architecture-GBF1 is essential for Golgi biogenesis, and the Golgi collapses and Golgi proteins relocate to the ER or to punctate structures adjacent to ER exit sites (ERES) in cells transfected with the catalytically inactive GBF1/E794K mutant, depleted of GBF1 by siRNA, or treated with the GBF1 inhibitors BFA and golgicide (9,17,22). We assessed the role of loopϾJ in GBF1 function by comparing Golgi architecture in cells expressing wild-type GFP-GBF1, GFP-GBF1/E794K, or GFP-GBF1/7A.…”

Section: Gbf1 With Mutations In Loopͼj Disruptsmentioning

confidence: 99%

“…Instead, we used FRAP to assess ARF binding to full-length GFP-GBF1/7A in vivo. GFP-GBF1 has been shown to rapidly cycle on and off Golgi membranes with a t1 ⁄ 2 of ϳ16 s, whereas the inactive GFP-GBF1/E794K that binds ARF but does not catalyze GDP to GTP exchange is stabilized on membranes with a FRAP of t1 ⁄ 2 ϳ53 s (18,22,29). Thus, if GFP-GBF1/7A binds ARF without catalyzing GDP to GTP exchange, its FRAP should be increased and similar to that of the inactive GBF1/E794K.…”

Section: Sec7 Domains With Mutations In Loopͼj Domentioning

confidence: 99%

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Novel C-terminal Motif within Sec7 Domain of Guanine Nucleotide Exchange Factors Regulates ADP-ribosylation Factor (ARF) Binding and Activation

Lowery

Szul

Seetharaman

et al. 2011

Journal of Biological Chemistry

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ADP-ribosylation factors (ARFs) and their activating guanine nucleotide exchange factors (GEFs) play key roles in membrane traffic and signaling. All ARF GEFs share a ϳ200-residue Sec7 domain (Sec7d) that alone catalyzes the GDP to GTP exchange that activates ARF. We determined the crystal structure of human BIG2 Sec7d. A C-terminal loop immediately following helix J (loop>J) was predicted to form contacts with helix H and the switch I region of the cognate ARF, suggesting that loop>J may participate in the catalytic reaction. Indeed, we identified multiple alanine substitutions within loop>J of the full length and/or Sec7d of two large brefeldin A-sensitive GEFs (GBF1 and BIG2) and one small brefeldin A-resistant GEF (ARNO) that abrogated binding of ARF and a single alanine substitution that allowed ARF binding but inhibited GDP to GTP exchange. Loop>J sequences are highly conserved, suggesting that loop>J plays a crucial role in the catalytic activity of all ARF GEFs. Using GEF mutants unable to bind ARF, we showed that GEFs associate with membranes independently of ARF and catalyze ARF activation in vivo only when membrane-associated. Our structural, cell biological, and biochemical findings identify loop>J as a key regulatory motif essential for ARF binding and GDP to GTP exchange by GEFs and provide evidence for the requirement of membrane association during GEF activity.

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“…Their mode of recruitment to the membrane is not well understood. GBF1 localizes to IC and Golgi, acting as a direct mediator of retrograde transport between these compartments and the ER Garcia-Mata et al 2003;Zhao et al 2006). This localization is directly dependent on an interaction between the GEF and Rab1b (Monetta et al 2007).…”

Section: Coat Recruitmentmentioning

confidence: 99%

COPI Budding within the Golgi Stack

Popoff

Adolf²,

Brügger³

et al. 2011

Cold Spring Harbor Perspectives in Biology

152

169

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The Golgi serves as a hub for intracellular membrane traffic in the eukaryotic cell. Transport within the early secretory pathway, that is within the Golgi and from the Golgi to the endoplasmic reticulum, is mediated by COPI-coated vesicles. The COPI coat shares structural features with the clathrin coat, but differs in the mechanisms of cargo sorting and vesicle formation. The small GTPase Arf1 initiates coating on activation and recruits en bloc the stable heptameric protein complex coatomer that resembles the inner and the outer shells of clathrin-coated vesicles. Different binding sites exist in coatomer for membrane machinery and for the sorting of various classes of cargo proteins. During the budding of a COPI vesicle, lipids are sorted to give a liquid-disordered phase composition. For the release of a COPI-coated vesicle, coatomer and Arf cooperate to mediate membrane separation.

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

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

Cited by 96 publications

References 70 publications

The Garz Sec7 domain guanine nucleotide exchange factor for Arf regulates salivary gland development in Drosophila

The Garz Sec7 domain guanine nucleotide exchange factor for Arf regulates salivary gland development in Drosophila

Novel C-terminal Motif within Sec7 Domain of Guanine Nucleotide Exchange Factors Regulates ADP-ribosylation Factor (ARF) Binding and Activation

COPI Budding within the Golgi Stack

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