Crystal structure of gamma-tubulin complex protein GCP4 provides insight into microtubule nucleation.
Guillet, V., Knibiehler, M., Gregory-Pauron, L., Remy, M.H., Chemin, C., Raynaud-Messina, B., Bon, C., Kollman, J.M., Agard, D.A., Merdes, A., Mourey, L.(2011) Nat Struct Mol Biol 18: 915-919
- PubMed: 21725292 
- DOI: https://doi.org/10.1038/nsmb.2083
- Primary Citation of Related Structures:  
3RIP - PubMed Abstract: 
Microtubule nucleation in all eukaryotes involves γ-tubulin small complexes (γTuSCs) that comprise two molecules of γ-tubulin bound to γ-tubulin complex proteins (GCPs) GCP2 and GCP3. In many eukaryotes, multiple γTuSCs associate with GCP4, GCP5 and GCP6 into large γ-tubulin ring complexes (γTuRCs). Recent cryo-EM studies indicate that a scaffold similar to γTuRCs is formed by lateral association of γTuSCs, with the C-terminal regions of GCP2 and GCP3 binding γ-tubulin molecules. However, the exact role of GCPs in microtubule nucleation remains unknown. Here we report the crystal structure of human GCP4 and show that its C-terminal domain binds directly to γ-tubulin. The human GCP4 structure is the prototype for all GCPs, as it can be precisely positioned within the γTuSC envelope, revealing the nature of protein-protein interactions and conformational changes regulating nucleation activity.
Organizational Affiliation: 
Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, Toulouse, France.