Differential binding of arfaptin 2/POR1 to ADP-ribosylation factors and Rac1

Ok Ho Shin, John H. Exton

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


We first identified arfaptin as a protein that bound to GTP-ARFs (especially ARF1). However, a second group reported that POR1, a truncated form of arfaptin, bound to GTP-Rac1. Therefore, we examined the possibility that arfaptin 2/POR1 was a common downstream effector for both ARF1 and Rac1. In this study, we found that constitutively active Rac1 or GTP-Rac1 showed negligible or no binding to arfaptin 2/POR1 in a yeast two-hybrid assay or a GST pull-down assay. However, wild-type or dominant negative Rac1 or Rac1 liganded to GDP showed strong binding. In contrast, constitutively active ARFs1, 5, and 6 showed binding, whereas the wild-type and dominant negative forms did not. Furthermore, the GTP-liganded ARFs bound arfaptin 2, whereas the GDP-bound forms showed little or no binding. Based on these observations, we suggest that arfaptin 2/POR1 is a target protein for GTP-ARFs and for GDP-Rac1, and that it may be involved in interactions between the Rac and ARF signaling pathways.

Original languageEnglish (US)
Pages (from-to)1267-1273
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number5
StatePublished - 2001
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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