The microtubule (MT) cytoskeleton plays important roles in many cellular processes. In vivo, MT nucleation is controlled by the γ-tubulin ring complex (γTuRC), a 2.1-MDa complex composed of γ-tubulin small complex (γTuSC) subunits. The mechanisms underlying the assembly of γTuRC are largely unknown. In yeast, the conserved protein Spc110p both stimulates the assembly of the γTuRC and anchors the γTuRC to the spindle pole body. Using a quantitative in vitro FRET assay, we show that γTuRC assembly is critically dependent on the oligomerization state of Spc110p, with higher-order oligomers dramatically enhancing the stability of assembled γTuRCs. Our in vitro findings were confirmed with a novel in vivo γTuSC recruitment assay. We conclude that precise spatial control over MT nucleation is achieved by coupling localization and higher-order oligomerization of the receptor for γTuRC.
© 2016 Lyon et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).