Structural highlights
FunctionTBG1_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 the principal microtubule nucleation template in vertebrates. Recent cryo-EM reconstructions visualized the intricate quaternary structure of the gamma-TuRC, containing more than thirty subunits, raising fundamental questions about gamma-TuRC assembly and the role of actin as an integral part of the complex. Here, we reveal the structural mechanism underlying modular gamma-TuRC assembly and identify a functional role of actin in microtubule nucleation. During gamma-TuRC assembly, a GCP6-stabilized core comprising GCP2-3-4-5-4-6 is expanded by stepwise recruitment, selective stabilization and conformational locking of four pre-formed GCP2-GCP3 units. Formation of the lumenal bridge specifies incorporation of the terminal GCP2-GCP3 unit and thereby leads to closure of the gamma-TuRC ring in a left-handed spiral configuration. Actin incorporation into the complex is not relevant for gamma-TuRC assembly and structural integrity, but determines gamma-TuRC geometry and is required for efficient microtubule nucleation and mitotic chromosome alignment in vivo. Modular assembly of the principal microtubule nucleator gamma-TuRC.,Wurtz M, Zupa E, Atorino ES, Neuner A, Bohler A, Rahadian AS, Vermeulen BJA, Tonon G, Eustermann S, Schiebel E, Pfeffer S Nat Commun. 2022 Jan 25;13(1):473. doi: 10.1038/s41467-022-28079-0. PMID:35078983[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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