Crystal structure of ?-tubulin complex protein GCP4 provides insight into microtubule nucleation.

ABSTRACT: Microtubule nucleation in all eukaryotes involves ?-tubulin small complexes (?TuSCs) that comprise two molecules of ?-tubulin bound to ?-tubulin complex proteins (GCPs) GCP2 and GCP3. In many eukaryotes, multiple ?TuSCs associate with GCP4, GCP5 and GCP6 into large ?-tubulin ring complexes (?TuRCs). Recent cryo-EM studies indicate that a scaffold similar to ?TuRCs is formed by lateral association of ?TuSCs, with the C-terminal regions of GCP2 and GCP3 binding ?-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 ?-tubulin. The human GCP4 structure is the prototype for all GCPs, as it can be precisely positioned within the ?TuSC envelope, revealing the nature of protein-protein interactions and conformational changes regulating nucleation activity.

SUBMITTER: Guillet V 

PROVIDER: S-EPMC3703858 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature