6V69

Structures of GCP4 and GCP5 in the native human gamma-tubulin ring complex

Summary for 6V69

• Entry DOI: 10.2210/pdb6v69/pdb
• EMDB information: 21060
• Descriptor: Gamma-tubulin complex component 5, Gamma-tubulin complex component 4 (2 entities in total)
• Functional Keywords: gcp, gcp4, gcp5, gamma-tubulin ring complex, gturc, g-turc, microtubule, microtubule nucleation, single particle cryo-em structure, structural protein
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 2
• Total formula weight: 194647.52

Authors

Wieczorek, M.,Urnavicius, L.,Ti, S.,Molloy, K.R.,Chait, B.T.,Kapoor, T.M. (deposition date: 2019-12-04, release date: 2020-01-01, Last modification date: 2025-05-28)

Primary citation

Wieczorek, M.,Urnavicius, L.,Ti, S.C.,Molloy, K.R.,Chait, B.T.,Kapoor, T.M.
Asymmetric Molecular Architecture of the Human gamma-Tubulin Ring Complex.
Cell, 180:165-175.e16, 2020

PubMed Abstract: The γ-tubulin ring complex (γ-TuRC) is an essential regulator of centrosomal and acentrosomal microtubule formation, yet its structure is not known. Here, we present a cryo-EM reconstruction of the native human γ-TuRC at ∼3.8 Å resolution, revealing an asymmetric, cone-shaped structure. Pseudo-atomic models indicate that GCP4, GCP5, and GCP6 form distinct Y-shaped assemblies that structurally mimic GCP2/GCP3 subcomplexes distal to the γ-TuRC "seam." We also identify an unanticipated structural bridge that includes an actin-like protein and spans the γ-TuRC lumen. Despite its asymmetric architecture, the γ-TuRC arranges γ-tubulins into a helical geometry poised to nucleate microtubules. Diversity in the γ-TuRC subunits introduces large (>100,000 Å) surfaces in the complex that allow for interactions with different regulatory factors. The observed compositional complexity of the γ-TuRC could self-regulate its assembly into a cone-shaped structure to control microtubule formation across diverse contexts, e.g., within biological condensates or alongside existing filaments.

PubMed: 31862189
DOI: 10.1016/j.cell.2019.12.007

Experimental method

ELECTRON MICROSCOPY (4.2 Å)