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Publication Abstract from PubMed

The gamma-tubulin ring complex (gamma-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 gamma-TuRC at approximately 3.8 A 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 gamma-TuRC "seam." We also identify an unanticipated structural bridge that includes an actin-like protein and spans the gamma-TuRC lumen. Despite its asymmetric architecture, the gamma-TuRC arranges gamma-tubulins into a helical geometry poised to nucleate microtubules. Diversity in the gamma-TuRC subunits introduces large (>100,000 A(2)) surfaces in the complex that allow for interactions with different regulatory factors. The observed compositional complexity of the gamma-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.

Asymmetric Molecular Architecture of the Human gamma-Tubulin Ring Complex.,Wieczorek M, Urnavicius L, Ti SC, Molloy KR, Chait BT, Kapoor TM Cell. 2019 Dec 13. pii: S0092-8674(19)31369-8. doi: 10.1016/j.cell.2019.12.007. PMID:31862189^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.