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Updated: Jan 18, 2026

Detection of Small GTPase Prenylation and GTP Binding Using Membrane Fractionation and GTPase-linked Immunosorbent Assay
Published on: November 11, 2018
Avl9 defines a family of GTPase-activating proteins that regulate diverse cell biological functions
Ryan C Vignogna1, J Christopher Fromme1
1Weill Institute for Cell and Molecular Biology & Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, USA.
Abstract:
Ras-related GTPases are molecular switches regulating hundreds of signaling and trafficking pathways in cells. Many GTPase regulators remain to be identified despite extensive genetic and biochemical screens. Here we present the results of computational protein-protein interaction screens and functional experiments identifying the DENN domain protein Avl9 as a GTPase-activating protein for Arf1. Avl9 is involved in secretion and cell migration, but its molecular function has not been characterized. We determined that Avl9 possesses robust Arf-GAP activity and is recruited to secretory vesicles by Rab8. We find that Avl9 function is conserved in humans and enhances cell migration. We propose that several other DENN domain proteins are also candidate GAPs, and we demonstrate that one candidate previously characterized as a Rab-GEF, DENND6A, exhibits strong Arf-GAP activity towards ARL8B, explaining its role in lysosome positioning. Collectively, this work uncovers a family of monomeric 'DENN GAP' proteins that regulate diverse cell biological pathways.
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