Ownership Structure and Corporate Performance: Australian Evidence

This paper seeks to analyse the relationship between ownership structure and corporate performance for fifty firms listed on the Australian Stock Exchange during 2002-2003. The study initially tests a two equation model similar to that in the existing literature, but is distinguished from prior literature by subsequently reclassifying leverage. By categorising leverage as an endogenous variable, an examination of the relationship between ownership and performance is undertaken through ordinary least squares and two stage least squares analysis of a three equation econometric model. Interestingly, empirical results illustrate the fact that managerial ownership impacts negatively on firm performance which is consistent with the management entrenchment hypothesis.Ownership Structure, Corporate Performance, Endogenous Leverage

Microtubule nucleation properties of single human γTuRCs explained by their Cryo-EM structure

The γ-tubulin ring complex (γTuRC) is the major microtubule nucleator in cells. The mechanism of its regulation is not understood. We purified human γTuRC and measured its nucleation properties in a total internal reflection fluorescence (TIRF) microscopy-based real-time nucleation assay. We find that γTuRC stably caps the minus ends of microtubules that it nucleates stochastically. Nucleation is inefficient compared with microtubule elongation. The 4 Å resolution cryoelectron microscopy (cryo-EM) structure of γTuRC, combined with crosslinking mass spectrometry analysis, reveals an asymmetric conformation with only part of the complex in a "closed" conformation matching the microtubule geometry. Actin in the core of the complex, and MZT2 at the outer perimeter of the closed part of γTuRC appear to stabilize the closed conformation. The opposite side of γTuRC is in an "open," nucleation-incompetent conformation, leading to a structural asymmetry explaining the low nucleation efficiency of purified human γTuRC. Our data suggest possible regulatory mechanisms for microtubule nucleation by γTuRC closure.This work was supported by the Francis Crick Institute, which receives its core funding from Cancer Research UK (FC001163 and FC0010065), the UK Medical Research Council (FC001163 and FC0010065), and the Wellcome Trust (FC001163 and FC0010065) to T.S. and A.C. The Wellcome Centre for Cell Biology is supported by core funding from the Wellcome Trust (203149). J. Rappsilber is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC 2008 – 390540038 – UniSysCat and 329673113. J. Roostalu. was supported by a Sir Henry Wellcome Postdoctoral Fellowship (100145/Z/12/Z) and M.A.C. is supported by a Marie Sk1odowska-Curie Postdoctoral Fellowship (agreement no. 845939). T.S. acknowledges support from the European Research Council (Advanced Grant, project 323042). A.C. receives funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 820102). T.C., J.A., J.W.M., and T.S. acknowledge also the support of the Spanish Ministry of Economy, Industry and Competitiveness to the CRG-EMBL partnership, the Centro de Excelencia Severo Ochoa and the CERCA Programme of the Generalitat de Cataluny

PP2A/B55 and Fcp1 regulate Greatwall and Ensa desphorylation during mitotic exit

Entry into mitosis is triggered by activation of Cdk1 and inactivation of its counteracting phosphatase PP2A/B55. Greatwall kinase inactivates PP2A/B55 via its substrates Ensa and ARPP19. Both Greatwall and Ensa/ARPP19 are regulated by phosphorylation, but the dynamic regulation of Greatwall activity and the phosphatases that control Greatwall kinase and its substrates are poorly understood. To address these questions we applied a combination of mathematical modelling and experiments using phospho-specific antibodies to monitor Greatwall, Ensa/ARPP19 and Cdk substrate phosphorylation during mitotic entry and exit. We demonstrate that PP2A/B55 is required for Gwl dephosphorylation at the essential Cdk site Thr194. Ensa/ARPP19 dephosphorylation is mediated by the RNA Polymerase II carboxy terminal domain phosphatase Fcp1. Surprisingly, neither Fcp1 nor PP2A appear to essential to dephosphorylate the bulk of mitotic Cdk1 substrates following Cdk1 inhibition. Taken together our results suggest a hierarchy of phosphatases coordinating Greatwall, Ensa/ARPP19 and Cdk substrate dephosphorylation during mitotic exit

Ownership structure and corporate performance : Australian evidence

This paper seeks to analyse the relationship between ownership structure and corporate performance for fifty firms listed on the Australian Stock Exchange during 2002-2003. The study initially tests a two equation model similar to that in the existing literature, but is distinguished from prior literature by subsequently reclassifying leverage. By categorising leverage as an endogenous variable, an examination of the relationship between ownership and performance is undertaken through ordinary least squares and two stage least squares analysis of a three equation econometric model. Interestingly, empirical results illustrate the fact that managerial ownership impacts negatively on firm performance which is consistent with the management entrenchment hypothesis.<br /