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

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.
Mesh Terms:
ADP-Ribosylation Factors, Adaptor Proteins, Signal Transducing, Animals, Base Sequence, Blotting, Western, CHO Cells, Carrier Proteins, Cricetinae, DNA, Complementary, Gene Expression, Genes, Dominant, Glutathione Transferase, Guanosine 5'-O-(3-Thiotriphosphate), Guanosine Diphosphate, Humans, Molecular Sequence Data, Mutagenesis, Protein Binding, Recombinant Fusion Proteins, Transfection, Two-Hybrid System Techniques, rac1 GTP-Binding Protein
Biochem. Biophys. Res. Commun.
Date: Aug. 03, 2001
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