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© The Rockefeller University Press,
0021-9525/2000//1513 $5.00
The Journal of Cell Biology, Volume 151, Number 7,
, 2000 1513-1524
Original Article |
Characterization and Reconstitution of Drosophila
-Tubulin Ring Complex Subunits
The
-tubulin ring complex (
TuRC) is important for microtubule nucleation from the centrosome. In addition to
-tubulin, the Drosophila
TuRC contains at least six subunits, three of which [Drosophila gamma ring proteins (Dgrips) 75/d75p, 84, and 91] have been characterized previously. Dgrips84 and 91 are present in both the small
-tubulin complex (
TuSC) and the
TuRC, while the remaining subunits are found only in the
TuRC. To study
TuRC assembly and function, we first reconstituted
TuSC using the baculovirus expression system. Using the reconstituted
TuSC, we showed for the first time that this subcomplex of the
TuRC has microtubule binding and capping activities. Next, we characterized two new
TuRC subunits, Dgrips128 and 163, and showed that they are centrosomal proteins. Sequence comparisons among all known
TuRC subunits revealed two novel sequence motifs, which we named grip motifs 1 and 2. We found that Dgrips128 and 163 can each interact with
TuSC. However, this interaction is insufficient for
TuRC assembly.
Key Words: centrosome microtubule
-tubulin grip Drosophila
© 2000 The Rockefeller University Press
Yixian Zheng, Howard Hughes Medical Institution, Carnegie Institution of Washington, 115 West University Parkway, Baltimore, MD 21210. Tel.: (410) 554-1232. Fax: (410) 243-6311. E-mail: zheng{at}ciwemb.eduDr. Kimberly Dej's present address is Whitehead Institute for Biomedical Research, Cambridge, MA 02142.
Abbreviations used in this paper: β-ME, β-mercaptoethanol; Dgrip, Drosophila gamma ring protein; EGS, ethylene glycol bis-succinimidyl succinate;
TuRC,
-tubulin ring complex;
TuSC,
-tubulin small complex; MT, microtubule.
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