Arfaptin interacts with ARF1, a small GTPase involved in vesicle budding at the Golgi complex and immature secretory granules. The structure of arfaptin shows that upon binding to a small GTPase, arfaptin forms an elongated, crescent-shaped dimer of three-helix coiled-coils [1]. The N-terminal region of ICA69 is similar to arfaptin [2].

1: The structural basis of Arfaptin-mediated cross-talk between Rac and Arf signalling pathways. Tarricone C, Xiao B, Justin N, Walker PA, Rittinger K, Gamblin SJ, Smerdon SJ; Nature 2001;411:215-219. PMID:11346801

2: Islet Cell Autoantigen of 69 kDa Is an Arfaptin-related Protein Associated with the Golgi Complex of Insulinoma INS-1 Cells. Spitzenberger F, Pietropaolo S, Verkade P, Habermann B, Lacas-Gervais S, Mziaut H, Pietropaolo M, Solimena M; J Biol Chem 2003;278:26166-26173. PMID:12682071