Mammalian Pins is a conformational switch that links NuMA to heterotrimeric G proteins

Cell. 2004 Nov 12;119(4):503-16. doi: 10.1016/j.cell.2004.10.028.


During asymmetric cell divisions, mitotic spindles align along the axis of polarization. In invertebrates, spindle positioning requires Pins or related proteins and a G protein alpha subunit. A mammalian Pins, called LGN, binds Galphai and also interacts through an N-terminal domain with the microtubule binding protein NuMA. During mitosis, LGN recruits NuMA to the cell cortex, while cortical association of LGN itself requires the C-terminal Galpha binding domain. Using a FRET biosensor, we find that LGN behaves as a conformational switch: in its closed state, the N and C termini interact, but NuMA or Galphai can disrupt this association, allowing LGN to interact simultaneously with both proteins, resulting in their cortical localization. Overexpression of Galphai or YFP-LGN causes a pronounced oscillation of metaphase spindles, and NuMA binding to LGN is required for these spindle movements. We propose that a related switch mechanism might operate in asymmetric cell divisions in the fly and nematode.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigens, Nuclear
  • Carrier Proteins / metabolism*
  • Cell Cycle
  • Cell Cycle Proteins
  • Cell Line
  • Cell Line, Transformed
  • Cell Polarity
  • Chromosomes / physiology
  • Dogs
  • Fluorescence Resonance Energy Transfer
  • GTP-Binding Protein alpha Subunits
  • Heterotrimeric GTP-Binding Proteins
  • Intracellular Signaling Peptides and Proteins
  • Microtubules / physiology
  • Models, Biological
  • Nuclear Matrix-Associated Proteins
  • Nuclear Proteins / metabolism*
  • Protein Binding
  • Protein Conformation
  • Saccharomyces cerevisiae
  • Spindle Apparatus / physiology*
  • Transfection


  • Antigens, Nuclear
  • Carrier Proteins
  • Cell Cycle Proteins
  • GPSM2 protein, human
  • GTP-Binding Protein alpha Subunits
  • Intracellular Signaling Peptides and Proteins
  • NUMA1 protein, human
  • Nuclear Matrix-Associated Proteins
  • Nuclear Proteins
  • Heterotrimeric GTP-Binding Proteins