HumanGBF1Is a Ubiquitously Expressed Gene of the Sec7 Domain Family Mapping to 10q24

Mansour, Sam J.; Herbrick, Jo-Anne; Scherer, Stephen W.; Melançon, Paul

doi:10.1006/geno.1998.5563

Cited by 22 publications

(21 citation statements)

References 19 publications

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“…Two mammalian ARF-GEFs of 200 kDa with a Sec7 domain have been characterized to date (48,49,51). Only one of these, GBF1 (48), was identified here as partitioning into Triton X-114.…”

Section: Discussionmentioning

confidence: 92%

“…This protein is the rat orthologue of a guanine nucleotide exchange factor (GEF) for ARFs termed GBF1 and related to products of the yeast genes GEA1 and GEA2 encoding Sec7 domains (48 -50). The Sec7 domain of this class of proteins effects GDP-GTP exchange and when associated with ARF-GDP can be targeted by the drug brefeldin A (48). However, the sequence-related protein p200ARF-GEF previously identified (51) and recently renamed BIG1 (52) was not identified.…”

Section: Identification Of Integral Membrane Proteins By Gas Phasementioning

confidence: 99%

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Proteomics Characterization of Abundant Golgi Membrane Proteins

Bell¹,

Ward²,

Blackstock³

et al. 2001

Journal of Biological Chemistry

228

208

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A mass spectrometric analysis of proteins partitioning into Triton X-114 from purified hepatic Golgi apparatus (84% purity by morphometry, 122-fold enrichment over the homogenate for the Golgi marker galactosyl transferase) led to the unambiguous identification of 81 proteins including a novel Golgi-associated protein of 34 kDa (GPP34). The membrane protein complement was resolved by SDS-polyacrylamide gel electrophoresis and subjected to a hierarchical approach using delayed extraction matrix-assisted laser desorption ionization mass spectrometry characterization by peptide mass fingerprinting, tandem mass spectrometry to generate sequence tags, and Edman sequencing of proteins. Major membrane proteins corresponded to known Golgi residents, a Golgi lectin, anterograde cargo, and an abundance of trafficking proteins including KDEL receptors, p24 family members, SNAREs, Rabs, a single ARF-guanine nucleotide exchange factor, and two SCAMPs. Analytical fractionation and gold immunolabeling of proteins in the purified Golgi fraction were used to assess the intra-Golgi and total cellular distribution of GPP34, two SNAREs, SCAMPs, and the trafficking proteins GBF1, BAP31, and ␣ 2 P24 identified by the proteomics approach as well as the endoplasmic reticulum contaminant calnexin. Although GPP34 has never previously been identified as a protein, the localization of GPP34 to the Golgi complex, the conservation of GPP34 from yeast to humans, and the cytosolically exposed location of GPP34 predict a role for a novel coat protein in Golgi trafficking.

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“…Two mammalian ARF-GEFs of 200 kDa with a Sec7 domain have been characterized to date (48,49,51). Only one of these, GBF1 (48), was identified here as partitioning into Triton X-114.…”

Section: Discussionmentioning

confidence: 92%

Section: Identification Of Integral Membrane Proteins By Gas Phasementioning

confidence: 99%

Proteomics Characterization of Abundant Golgi Membrane Proteins

Bell¹,

Ward²,

Blackstock³

et al. 2001

Journal of Biological Chemistry

228

208

View full text Add to dashboard Cite

show abstract

“…Whether the remaining cytosolic BIG1 and BIG2 (25-30% of the total) are associated with other proteins in different kinds of complexes is among many questions that need to be addressed, as is, for example, the physical state of BIG1 and BIG2 in the Golgi membrane. Yeast Gea1, a 160-kDa protein of 1,408 amino acids, was present in a 500-to 600-kDa complex (19), and GBF1, the mammalian homologue of yeast Gea1͞ Gea2 (30), may also exist in multi-protein complexes.…”

Section: Discussionmentioning

confidence: 99%

Identification and localization of two brefeldin A-inhibited guanine nucleotide-exchange proteins for ADP-ribosylation factors in a macromolecular complex

Yamaji

Adamik

Takeda

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

112

116

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Two brefeldin A (BFA)-inhibited guanine nucleotide-exchange proteins for ADP-ribosylation factors, 200-kDa BIG1 and 190-kDa BIG2, were copurified from bovine brain cytosol associated with >670-kDa macromolecular complexes. When observed by immunofluorescence in HeLa S3 and HepG2 cells, endogenous BIG1 and coexpressed BIG2 were distributed in a punctate pattern throughout the cytosol, and also concentrated in the perinuclear region, where endogenous BIG1 and BIG2 each partially colocalized with Golgispecific 58K protein and ␥-adaptin. On Western blot analysis, both BIG1 and BIG2 were clearly more abundant in the cytosol than in the microsomal fractions. After density gradient centrifugation of a microsomal fraction, BIG1 and BIG2 were recovered in the same fraction as ␤-COP, a marker for Golgi membranes. When cytosol from HeLa S3 cells was subjected to gel filtration and fractions were analyzed by Western blotting, the largest percentages of both BIG1 and BIG2 were detected in fractions containing proteins with a molecular mass of >670 kDa. Western blotting using anti-peptide antibodies specific for BIG1 or BIG2 demonstrated that Ϸ70% of BIG2 was immunoprecipitated along with 100% of BIG1 by the anti-BIG1 IgG, and Ϸ75% of BIG1 was coprecipitated with 100% of BIG2 by the anti-BIG2 IgG. All observations were consistent with the conclusion that significant fractions of BIG1 and BIG2 exist as components of the same macromolecular complexes in bovine brain cytosol and are similarly localized in cultured cells.

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“…GNOM-like, Arabidopsis GNOM-like putative protein (Sato et al, 1998); H.s. GBF-1, human GBF1 (Mansour et al, 1998); B.t. GEP, bovine Sec7-like GEP (Morinaga et al, 1997); S.c. Gea1p and Gea2p, budding (Figure 5B).…”

Section: Specific Interaction Between Gnom and Cyp5 Is Mediated By Thmentioning

confidence: 99%

A Conserved Domain of the Arabidopsis GNOM Protein Mediates Subunit Interaction and Cyclophilin 5 Binding

et al. 2000

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The Arabidopsis GNOM protein, a guanine nucleotide exchange factor (GEF) that acts on ADP ribosylation factor (ARF)-type G proteins, is required for coordination of cell polarity along the apical-basal embryo axis. Interallelic complementation of gnom mutants suggested that dimerization is involved in GNOM function. Here, direct interaction between GNOM molecules is demonstrated in vitro and by using a yeast two-hybrid system. Interaction was confined to an N-terminal domain conserved within a subgroup of large ARF GEFs. The same domain mediated in vitro binding to cyclophilin 5 (Cyp5), which was identified as a GNOM interactor in two-hybrid screening. Cyp5 displayed peptidylprolyl cis / trans -isomerase and protein refolding activities that were sensitive to cyclosporin A. Cyp5 protein accumulated in several plant organs and, like GNOM, was partitioned between cytosolic and membrane fractions. Cyp5 protein was also expressed in the developing embryo. Our results suggest that Cyp5 may regulate the ARF GEF function of the GNOM protein during embryogenesis. INTRODUCTIONThe GNOM gene was identified by multiple mutant alleles in a search for mutations affecting body organization of the Arabidopsis embryo . All gnom alleles are defective in establishing the apical-basal axis of embryo polarity. The earliest defect observed in the gnom embryo, which is a perturbed division of the zygote, is followed by irregular cell division and elongation patterns at subsequent stages (Mayer et al., 1993). gnom seedlings lack a root, are defective in coordinated alignment of vascular cells, and display variably reduced apical structures (Mayer et al., 1993). These alterations have been attributed to defects in the establishment of coordinated cell polarity along the apical-basal axis in early embryos (Steinmann et al., 1999). Cloning of the GNOM gene (also called EMB30 ) revealed sequence similarity to the yeast vesicle trafficking protein Sec7p, including a central region called the Sec7 domain (Shevell et al., 1994;Busch et al., 1996). Proteins with Sec7 domains catalyze guanine nucleotide exchange on small GTP binding proteins of the ADP ribosylation factor (ARF) family required for vesicle coating in membrane trafficking (Chardin et al., 1996;Sata et al., 1998;Springer et al., 1999).Guanine nucleotide exchange factors (GEFs) that act on ARFs (ARF GEFs) group into small and large family members, and large ARF GEFs include the yeast proteins Gea1p, Gea2p, and Sec7p (Chardin et al., 1996;Peyroche et al., 1996;Sata et al., 1998). GNOM is a membrane-associated, functional ARF GEF of the Gea type, suggesting its involvement in vesicular trafficking (Steinmann et al., 1999). Apart from the Sec7 domain, large ARF GEFs contain as yet functionally uncharacterized N-and C-terminal regions . In the case of GNOM, however, there is genetic evidence for subunit interaction, because gnom alleles with different mutations in the Sec7 domain exhibit full complementation (Busch et al., 1996). In this study, we demonstrate a physical interaction of...

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HumanGBF1Is a Ubiquitously Expressed Gene of the Sec7 Domain Family Mapping to 10q24

Cited by 22 publications

References 19 publications

Proteomics Characterization of Abundant Golgi Membrane Proteins

Proteomics Characterization of Abundant Golgi Membrane Proteins

Identification and localization of two brefeldin A-inhibited guanine nucleotide-exchange proteins for ADP-ribosylation factors in a macromolecular complex

A Conserved Domain of the Arabidopsis GNOM Protein Mediates Subunit Interaction and Cyclophilin 5 Binding

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