Published online February 26, 2007
doi:10.1083/jcb.200608128
The Journal of Cell Biology, Vol. 176, No. 5, 641-651
The Rockefeller University Press, 0021-9525 $30.00
© 2007 Kim et al.
Microtubule binding by dynactin is required for microtubule organization but not cargo transport
Hwajin Kim1,
Shuo-Chien Ling1,
Gregory C. Rogers2,
Comert Kural3,
Paul R. Selvin3,4,
Stephen L. Rogers2, and
Vladimir I. Gelfand1
1 Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
2 Department of Biology, University of North Carolina, Chapel Hill, NC 27599
3 Biophysics Center and 4 Physics Department, University of Illinois, Urbana, IL 61801
Correspondence to Vladimir I. Gelfand: vgelfand{at}northwestern.edu
Dynactin links cytoplasmic dynein and other motors to cargo and is involved in organizing radial microtubule arrays. The largest subunit of dynactin, p150glued, binds the dynein intermediate chain and has an N-terminal microtubule-binding domain. To examine the role of microtubule binding by p150glued, we replaced the wild-type p150glued in Drosophila melanogaster S2 cells with mutant
N-p150 lacking residues 1200, which is unable to bind microtubules. Cells treated with cytochalasin D were used for analysis of cargo movement along microtubules. Strikingly, although the movement of both membranous organelles and messenger ribonucleoprotein complexes by dynein and kinesin-1 requires dynactin, the substitution of full-length p150glued with
N-p150glued has no effect on the rate, processivity, or step size of transport. However, truncation of the microtubule-binding domain of p150glued has a dramatic effect on cell division, resulting in the generation of multipolar spindles and free microtubule-organizing centers. Thus, dynactin binding to microtubules is required for organizing spindle microtubule arrays but not cargo motility in vivo.
Abbreviations used in this paper: dFMRP, Drosophila homologue of the fragile X mental retardation protein; DHC, dynein heavy chain; KHC, kinesin heavy chain; mRFP, monomeric red fluorescent protein; mRNP, messenger RNP; MTOC, microtubule-organizing center; UTR, untranslated region.

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