Structural highlights
Function[TBG1_HUMAN] Tubulin is the major constituent of microtubules. The gamma chain is found at microtubule organizing centers (MTOC) such as the spindle poles or the centrosome. Pericentriolar matrix component that regulates alpha/beta chain minus-end nucleation, centrosome duplication and spindle formation. Publication Abstract from PubMedThe 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. References
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