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. Author manuscript; available in PMC: 2022 Oct 31.
Published in final edited form as: Annu Rev Cell Dev Biol. 2022 Jun 27;38:1–23. doi: 10.1146/annurev-cellbio-120420-114559

Figure 2.

Figure 2

Orthologous branching factors across model organisms. (a) The nucleator γ-TuRC consists of a spiral of 14 γ-tubulins scaffolded by GCPs. Mzt/GCP complexes occupy diverse positions throughout the ring, binding the accessory subunit NEDD1 and the localizer/activator γ-TuNA. The cartoon of γ-TuRC is based on data from Consolati et al. (2020), Liu et al. (2020), and Wieczorek et al. (2020a,b). (b) The augmin complex is an “h” shaped hetero-octamer separable into the MT-binding tetramer I/II (T-I/II) and γ-TuRC-binding tetramer III (T-III). Augmin is lost in yeast, and low sequence homology prevents four of the eight Drosophila augmin subunits (Dgt2, Dgt7, Dgt8, and Dgt9) from being matched to their vertebrate and plant counterparts. The 2D classification of human augmin was reproduced with permission from Hsia et al. (2014); the 2D classification of Xenopus augmin was reproduced from Song et al. (2018). (c) The microtubule polymerase and nucleator XMAP215 consists of multiple tubulin-binding TOG domains, where TOG1–3 bind soluble tubulin, TOG4–5 bind polymerized tubulin, and TOG6 binds γ-tubulin. (d) TPX2, a large, poorly-ordered protein, binds tubulin in various forms, as well as itself, γ-TuRC, and importin regulatory proteins. The cartoon of TPX2 is based on data from Alfaro-Aco et al. (2017). Abbreviations: γ-TuNA, γ-tubulin nucleator activator; γ-TuRC, γ-tubulin ring complex; ACT, actin; Alp, altered polarity; AUG, augmin; CCDC, coiled-coil domain containing protein; Cep, centrosomal protein; chTOG, colonic and hepatic tumor overexpressed gene; Dgp, Drosophila γ-ring protein; Dgt, dim γ-tubulin; Dgrip, Drosophila γ-ring protein; EDE, endosperm defective; FAM, family with sequence similarity; GCP, γ-tubulin complex protein; Gfh, GCP4 homolog; GIP, GCP3-interacting protein; Haus, homologous to augmin subunit; Hice, Hec1-interacting and centrosome-associated; KIAA, Kazusa cDNA sequencing project gene; Klp, kinesin-like protein; Mei, meiotic mutant; Mod, morphology defective; MOR, microtubule organization; Msps, minispindles; MT, microtubule; Mzt, mitotic spindle organizing proteins associated with a ring of γ-tubulin; NEDD, neural precursor cell expressed, developmentally-downregulated; NME, non-metastatic cells; Spc, spindle pole component; Stu, suppressor of tubulin; Tam, transcript altered in meiosis; TPX, targeting protein for Xenopus kinesin-like protein; TUB, tubulin; UCHL5, ubiquitin carboxy-terminus hydrolase isozyme L5; XMAP215, Xenopus MT-associated protein of 215 kDa.