The TOGp protein is a new human microtubule-associated protein homologous to the Xenopus XMAP215.
We have recently identified a 6,449 bp cDNA, termed colonic, hepatic tumor over-expressed gene (ch-TOG), that is highly expressed in human tumors and brain. Its single open reading frame encodes a putative 218,000 Da polypeptide, TOGp. Antibodies generated against a bacterially expressed TOGp fragment specifically recognize a 218, 000 Da polypeptide in two human cell lines and in brain. Immunofluorescence microscopy using affinity-purified TOGp antibodies revealed that the distribution of TOGp was dependent upon the cell cycle. During interphase, TOGp was found concentrated in the perinuclear cytoplasm, where it co-localized with ER markers. In contrast anti-TOGp antibodies stained centrosomes and spindles in mitotic cells. TOGp co-sedimented with taxol-stabilized microtubules in vitro. Moreover, a TOGp enriched fraction promotes microtubule assembly both in solution and from nucleation centers. Finally, sequence comparison and immunologic cross-reaction suggest that TOGp is homologous to XMAP215, a previously described microtubule associated protein (MAP) from Xenopus eggs. These results suggest that TOGp is a MAP and that TOGp/XMAP215 may be necessary for microtubules rearrangements and spindle assembly in rapidly dividing cells.
Charrasse
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INSERM Unite 128, 34293 Montpellier, France.
Schroeder
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Gauthier-Rouviere
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Ango
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F
Cassimeris
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Gard
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Larroque
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D000818:Animals; D000918:Antibody Specificity; D003429:Cross Reactions; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D006801:Humans; D007399:Interphase / Q000502:physiology; D008861:Microsomes / Q000737:chemistry; D008869:Microtubule-Associated Proteins / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D008941:Spindle Apparatus / Q000378:metabolism; D013347:Subcellular Fractions / Q000737:chemistry; D029867:Xenopus Proteins; D014982:Xenopus laevis
C486738:CKAP5 protein, Xenopus; C454180:CKAP5 protein, human; D008869:Microtubule-Associated Proteins; D029867:Xenopus Proteins