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The Human EMAP-like Protein-70 (ELP70) Is a Microtubule Destabilizer That Localizes to the Mitotic Apparatus
In this report, we show that the e chinoderm m icrotubule (MT)- a ssociated p rotein (EMAP) and related E MAP- l ike p roteins (ELPs) share a similar domain organization with a highly conserved h ydrophobic ELP (HELP) domain and a large tryptophan-aspartic acid (WD) repeat domain. To determine the f...
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Published in: | The Journal of biological chemistry 2002-01, Vol.277 (2), p.1301-1309 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | In this report, we show that the e chinoderm m icrotubule (MT)- a ssociated p rotein (EMAP) and related E MAP- l ike p roteins (ELPs) share a similar domain organization with a highly conserved h ydrophobic ELP (HELP) domain and a large tryptophan-aspartic acid (WD) repeat domain. To determine the function of mammalian ELPs, we generated
antibodies against a 70-kDa human ELP and showed that ELP70 coassembled with MTs in HeLa cell extracts and colocalized with
MTs in the mitotic apparatus. To determine whether ELP70 bound to MTs directly, human ELP70 was expressed and purified to
homogeneity from baculovirus-infected Sf9 cells. Purified ELP70 bound to purified MTs with a stoichiometry of 0.40 ± 0.04
mol of ELP70/mol of tubulin dimer and with an intrinsic dissociation constant of 0.44 ± 0.13 μ m . Using a nucleated assembly assay and video-enhanced differential interference contrast microscopy, we demonstrated that
ELP70 reduced seeded nucleation, reduced the growth rate, and promoted MT catastrophes in a concentration-dependent manner.
As a result, ELP70-containing MTs were significantly shorter than MTs assembled from tubulin alone. These data indicate that
ELP70 is a novel MT destabilizer. A lateral destabilization model is presented to describe ELP70's effects on microtubules. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M106628200 |