biostudies-literatureAher ANIGMS NIH HHS1124-1133https://www.ebi.ac.uk/biostudies/studies/S-EPMC11257807biostudies-literatureUnknown31(7)Microtubules are composed of α-tubulin and β-tubulin dimers positioned head-to-tail to form protofilaments that associate laterally in varying numbers. It is not known how cellular microtubules assemble with the canonical 13-protofilament architecture, resulting in micrometer-scale α/β-tubulin tracks for intracellular transport that align with, rather than spiral along, the long axis of the filament. We report that the human ~2.3 MDa γ-tubulin ring complex (γ-TuRC), an essential regulator of microtubule formation that contains 14 γ-tubulins, selectively nucleates 13-protofilament microtubules. Cryogenic electron microscopy reconstructions of γ-TuRC-capped microtubule minus ends reveal the extensive intra-domain and inter-domain motions of γ-TuRC subunits that accommodate luminal bridge comNature structural & molecular biologyStructure of the γ-tubulin ring complex-capped microtubule.PMC11257807R35 GM130234Aher AKapoor TMUrnavicius LXue ANeselu KfalseStructure of the γ-tubulin ring complex-capped microtubule.Microtubules are composed of α-tubulin and β-tubulin dimers positioned head-to-tail to form protofilaments that associate laterally in varying numbers. It is not known how cellular microtubules assemble with the canonical 13-protofilament architecture, resulting in micrometer-scale α/β-tubulin tracks for intracellular transport that align with, rather than spiral along, the long axis of the filament. We report that the human ~2.3 MDa γ-tubulin ring complex (γ-TuRC), an essential regulator of microtubule formation that contains 14 γ-tubulins, selectively nucleates 13-protofilament microtubules. Cryogenic electron microscopy reconstructions of γ-TuRC-capped microtubule minus ends reveal the extensive intra-domain and inter-domain motions of γ-TuRC subunits that accommodate luminal bridge com2024-01-01T00:00:00Z2024 Jul2026-06-02T01:07:15.551Z2026-05-24T03:07:27.279ZS-EPMC112578073860966110.1038/s41594-024-01264-z