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Updated: Jan 21, 2026

In Vitro Polymerization of F-actin on Early Endosomes
Published on: August 28, 2017
YFR016c/Aip5 is part of an actin nucleation complex in yeast
Oliver Glomb1, Lara Bareis1, Nils Johnsson2
1Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany.
Abstract:
The polarisome comprises a network of proteins that organizes polar growth in yeast and filamentous fungi. The yeast formin Bni1 and the actin nucleation-promoting factor Bud6 are subunits of the polarisome that together catalyze the formation of actin cables below the tip of yeast cells. We identified YFR016c (Aip5) as an interaction partner of Bud6 and the polarisome scaffold Spa2. Yeast cells lacking Aip5 display a reduced number of actin cables. Aip5 binds with its N-terminal region to Spa2 and with its C-terminal region to Bud6. Both interactions collaborate to localize Aip5 at bud tip and neck, and are required to stimulate the formation of actin cables. Our experiments characterize Aip5 as a novel subunit of a complex that regulates the number of actin filaments at sites of polar growth.
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