Structural highlights
FunctionTBA1B_HUMAN Tubulin is the major constituent of microtubules. It binds two moles of GTP, one at an exchangeable site on the beta chain and one at a non-exchangeable site on the alpha chain. Publication Abstract from PubMedMicrotubules are composed of alpha-tubulin and beta-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 alpha/beta-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 gamma-tubulin ring complex (gamma-TuRC), an essential regulator of microtubule formation that contains 14 gamma-tubulins, selectively nucleates 13-protofilament microtubules. Cryogenic electron microscopy reconstructions of gamma-TuRC-capped microtubule minus ends reveal the extensive intra-domain and inter-domain motions of gamma-TuRC subunits that accommodate luminal bridge components and establish lateral and longitudinal interactions between gamma-tubulins and alpha-tubulins. Our structures suggest that gamma-TuRC, an inefficient nucleation template owing to its splayed conformation, can transform into a compacted cap at the microtubule minus end and set the lattice architecture of cellular microtubules. Structure of the gamma-tubulin ring complex-capped microtubule.,Aher A, Urnavicius L, Xue A, Neselu K, Kapoor TM Nat Struct Mol Biol. 2024 Jul;31(7):1124-1133. doi: 10.1038/s41594-024-01264-z. , Epub 2024 Apr 12. PMID:38609661[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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