GBF1: A novel Golgi-associated BFA-resistant guanine nucleotide exchange factor that displays specificity for ADP-ribosylation factor 5

Alejandro Claude, Bao Ping Zhao, Craig E. Kuziemsky, Sophie Dahan, Scott J. Berger, Jian Ping Yan, Adrian D. Armold, Eric M. Sullivan, Paul Melançon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

157 Citations (Scopus)

Abstract

Expression cloning from a cDNA library prepared from a mutant CHO cell line with Golgi-specific resistance to Brefeldin A (BFA) identified a novel 206-kD protein with a Sec7 domain termed GBF1 for Golgi BFA resistance factor 1. Overexpression of GBF1 allowed transfected cells to maintain normal Golgi morphology and grow in the presence of BFA. Golgi-enriched membrane fractions from such transfected cells displayed normal levels of ADP ribosylation factors (ARFs) activation and coat protein recruitment that were, however, BFA resistant. Hexahistidine-tagged-GBF1 exhibited BFA-resistant guanine nucleotide exchange activity that appears specific towards ARF5 at physiological Mg2+ concentration. Characterization of cDNAs recovered from the mutant and wild-type parental lines established that transcripts in these cells had identical sequence and, therefore, that GBF1 was naturally BFA resistant. GBF1 was primarily cytosolic but a significant pool colocalized to a perinuclear structure with the β-subunit of COPI. Immunogold labeling showed highest density of GBF1 over Golgi cisternae and significant labeling over pleiomorphic smooth vesiculotubular structures. The BFA-resistant nature of GBF1 suggests involvement in retrograde traffic.

Original languageEnglish
Pages (from-to)71-84
Number of pages14
JournalJournal of Cell Biology
Volume146
Issue number1
DOIs
Publication statusPublished - 12 Jul 1999
Externally publishedYes

Keywords

  • ADP-ribosylation factor
  • Brefeldin A
  • Golgi complex
  • Protein traffic
  • Sec7

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