AI Article Synopsis
- Membrane-sculpting BAR domains form crescent-shaped homodimers that can sense and shape membrane curvature, particularly due to their positively charged concave face.
- Recent findings show that Arfaptin-2, initially recognized for its interaction with Arf and Rac1 GTPases, also binds to Arl1 through its BAR domain and is recruited to Golgi membranes, where it induces the formation of membrane tubules.
- The crystal structure of the Arfaptin-2 BAR homodimer reveals Arl1 binding on both sides, which allows the concave face to remain available for membrane interaction, suggesting that Arl1 may disrupt Rac1 binding and influence membrane association dynamics.
Article Abstract
Membrane-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.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3408144 | PMC |
| http://dx.doi.org/10.1074/jbc.M112.365783 | DOI Listing |
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