Structural highlights
Function[ARL1_HUMAN] GTP-binding protein that has very low efficiency as allosteric activator of the cholera toxin catalytic subunit, an ADP-ribosyltransferase. Can activate phospholipase D with very low efficiency. Important for normal function of the Golgi apparatus.[1] [ARFP2_HUMAN] Putative target protein of ADP-ribosylation factor. Involved in membrane ruffling. Publication Abstract from PubMedMembrane-sculpting BAR (Bin/Amphiphysin/Rvs) domains form a crescent-shaped homodimer that can sense and induce membrane curvature through its positively charged concave face. We have recently shown that Arfaptin-2, which was originally identified as a binding partner for the Arf and Rac1 GTPases, binds to Arl1 through its BAR domain and is recruited onto Golgi membranes. There, Arfaptin-2 induces membrane tubules. Here, we report the crystal structure of the Arfaptin-2 BAR homodimer in complex with two Arl1 molecules bound symmetrically to each side, leaving the concave face open for membrane association. The overall structure of the Arl1.Arfaptin-2 BAR complex closely resembles that of the PX-BAR domain of sorting nexin 9, suggesting similar mechanisms underlying BAR domain targeting to specific organellar membranes. The Arl1.Arfaptin-2 BAR structure suggests that one of the two Arl1 molecules competes with Rac1, which binds to the concave face of the Arfaptin-2 BAR homodimer and may hinder its membrane association. Structural basis for membrane binding specificity of the Bin/Amphiphysin/Rvs (BAR) domain of Arfaptin-2 determined by Arl1 GTPase.,Nakamura K, Man Z, Xie Y, Hanai A, Makyio H, Kawasaki M, Kato R, Shin HW, Nakayama K, Wakatsuki S J Biol Chem. 2012 Jul 20;287(30):25478-89. doi: 10.1074/jbc.M112.365783. Epub, 2012 Jun 7. PMID:22679020[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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