High impact information on gammaTub23C

• In A. nidulans, gamma-tubulin is essential for nuclear division and microtubule assembly and is associated with the spindle pole body, the fungal microtubule organizing center [1].
• By low stringency hybridizations we have cloned cDNAs from D. melanogaster and H. sapiens, the predicted products of which share more than 66% amino acid identity with A. nidulans gamma-tubulin. gamma-Tubulin-specific antibodies stained centrosomes of Drosophila, human, and mouse cell lines [1].
• Thus, Asp appears to hold together the microtubule-nucleating gamma-tubulin ring complexes that organize the mitotic centrosome [2].
• The NH2-terminal half of CNN interacts with gamma-tubulin, and induces cytoplasmic foci that can initiate microtubule nucleation in vivo and in vitro in both Drosophila and mammalian cells [3].
• These results suggest that Aurora-A regulates centrosome assembly by controlling the CNN's ability to targeting and/or anchoring gamma-tubulin to the centrosome and organizing microtubule-nucleating sites via its interaction with the COOH-terminal sequence of CNN [3].

Biological context of gammaTub23C

• Gamma-tub37CD is constantly detected at the centrosome and absent in the mitotic spindle, while gamma-tub23C is extensively recruited to the centrosome during mitosis and relocalizes in the mitotic spindle [4].
• To gain a better understanding of their molecular nature, we have studied the centrosomal component gamma-tubulin during Drosophila oogenesis [5].
• With the exception of gamma-tubulin, Dgp71WD is the only gammaTuRC component identified to date that does not contain the grip motifs, which are signature sequences conserved in gammaTuRC components [6].
• The unusual disk- or ring-shaped central spindle pole body forms de novo in the center of the elongated meiosis I spindle, followed by formation of the central spindle poles. gamma-Tubulin transiently localizes to the central spindle pole body, implying that the body acts as a microtubule nucleating center for assembly of the central poles [7].
• This conclusion is based on the identification and phenotypic characterization of a mutant allele of the gamma-tubulin gene located at region 23C of the polytene chromosome map [8].

Anatomical context of gammaTub23C

• The gamma-tubulin ring complex (gammaTuRC) is important for microtubule nucleation from the centrosome [9].
• The gamma-tubulin ring complex (gammaTuRC) forms an essential template for microtubule nucleation in animal cells [10].
• Using specific nucleotidic and immunological probes, we have demonstrated that the two divergent Drosophila gamma-tubulins, gamma-tub23C and gamma-tub37CD, are expressed in cultured cells [4].
• Gamma-tub23C is present in the soluble gamma-tubulin small complexes (10S) and gamma-tubulin big complexes (35S) and is loosely associated to the cytoskeleton [4].
• The combination of loss-of-function mutant alleles for the two gamma-tubulin genes leads to mitotic defects in female germ cells, resulting in agametic ovaries [5].

Associations of gammaTub23C with chemical compounds

• Coexpression of any of these grip motif-containing proteins with gamma-tubulin promotes gamma-tubulin binding to guanine nucleotide [6].

Other interactions of gammaTub23C

• Aurora-A and CNN are mutually dependent for localization at spindle poles, which is required for proper targeting of gamma-tubulin and other centrosomal components to the centrosome [3].
• In addition to gamma-tubulin, the gammaTuSC contains Dgrip84 and Dgrip91, two proteins homologous to the Spc97/98p protein family [11].
• Despite the marked depletion of gamma-tubulin, the pericentriolar proteins CP190 and centrosomin were recruited to the spindle pole(s), where they formed three or four dots, suggesting the presence of several centrioles [12].
• Electron microscopy on purified syncytial centrosomes shows that Miranda is located on the pericentriolar material along with gamma-tubulin [13].
• We show that gamma-tubulin binds to a microtubule column as part of a complex, and a substantial fraction of this gamma-tubulin is tightly associated with DMAP60 [14].

Analytical, diagnostic and therapeutic context of gammaTub23C

• Yet, immunofluorescence revealed that spindles in larval brains of urchin mutants in Drosophila were frequently monastral but bipolar; the astral pole contained a centrosome while the opposing anastral pole showed neither gamma tubulin nor a radial array of astral microtubules [15].

References